# How to Organize Mendeley References by Theme
## Quick Answer

- Use Mendeley tags and smart collections to assign each reference to multiple emerging themes, avoiding rigid folder hierarchies that force one location per paper.
- Build your thematic structure iteratively: start with broad tags, review your library, then split or merge tags as your narrative themes crystallize.
- Mendeley Desktop and Mendeley Reference Manager differ in sync and tagging features, so verify your version supports the workflow before reorganizing a large library.

## Why Thematic Organization Matters for Narrative Reviews

Narrative reviews differ from systematic reviews in how they treat the literature. A systematic review follows a predefined protocol with explicit inclusion criteria and reproducible search strategies. A narrative review synthesizes evidence across a topic to identify patterns, tensions, and gaps. The organizing principle is the argument you are building, not the database you searched.

When you organize references by theme, you are mapping the intellectual structure of your review. Each theme represents a claim, a debate, or a body of evidence that your narrative will address. A single study can inform multiple themes. A paper on antimicrobial resistance in livestock might support a theme on treatment failure, a theme on farm management practices, and a theme on policy interventions. A folder structure forces you to choose one location for that paper. A tagging system lets the paper appear in all three thematic groups simultaneously.

The practical problem is that themes emerge as you read. You may start with a working title and a rough outline, but the literature will reshape your thinking. A paper you initially file under "diagnosis" may later become central to your "differential diagnosis" theme. A study you tagged as "prevention" may end up supporting your "economic impact" section. If you have placed each reference in a single folder, you must physically move it every time your thinking changes. If you have tagged it, you simply add or remove a tag.

Mendeley supports this workflow through two mechanisms: tags and smart collections. Tags are free-form labels you assign to individual references. Smart collections are saved searches that automatically gather references matching your criteria. Both allow a reference to belong to multiple groups. Neither forces you to choose a single location.

The limitation is that Mendeley's tagging interface is less polished than its folder system. Tags are not hierarchical, so you cannot nest a tag inside another tag. You cannot rename a tag across your entire library in one operation. You must plan your tag vocabulary carefully and accept that some cleanup will be manual.

## Core Principles of Thematic Reference Organization

### Tags Represent Concepts, Not Locations

A tag should name a concept that appears in your narrative. Examples include "treatment failure," "diagnostic accuracy," "economic burden," "welfare outcomes," "regulatory context," and "study design." The tag is a property of the reference, not a place where the reference lives. This distinction matters because a reference can have many properties but can only be stored in one folder.

When you tag a reference, you are recording a judgment about how that paper contributes to your review. That judgment should be revisable. As your understanding of the literature deepens, you may decide that a paper belongs under a different or additional theme. The tag system supports this revision because you can add or remove tags without moving the reference.

### Smart Collections Automate Routine Grouping

Smart collections are saved searches. You define criteria, and Mendeley automatically adds references that match. For example, you can create a smart collection for "systematic reviews" that includes any reference with the tag "systematic review." You can create a smart collection for "bovine respiratory disease" that includes references whose title, abstract, or tags contain that phrase.

Smart collections are useful for themes that have clear inclusion criteria. They are less useful for themes that require judgment. A theme like "management implications" may include references that do not share a common keyword. You would need to tag each reference manually and then build a smart collection based on that tag.

The practical workflow combines both tools. Use tags to record your judgment about each reference. Use smart collections to assemble references that share a tag or a keyword. Use regular collections only when you need a fixed list, such as a set of references you plan to cite in a specific section.

### Thematic Organization Is Iterative

Your first pass at tagging will be rough. You will create tags that are too broad or too narrow. You will tag some references inconsistently. This is expected. The goal is not to create a perfect taxonomy on the first attempt. The goal is to create a working structure that you can refine as your narrative develops.

A practical workflow is to tag every reference as you add it to your library. Use a small set of broad tags initially. After you have read a portion of your literature, review your tags and split the broad tags into more specific ones. For example, you may start with a tag "treatment" and later split it into "treatment failure," "treatment protocols," and "treatment economics." You can apply the new tags to the references that need them.

This iterative process is the core of thematic organization. It mirrors the way a narrative review develops. Your themes emerge from the literature, and your organization should reflect that emergence.

## Setting Up Mendeley for Thematic Work

### Choose Your Mendeley Version

Mendeley Desktop and Mendeley Reference Manager have different feature sets. Mendeley Reference Manager is the current version and supports tags and smart collections. Mendeley Desktop is the legacy version and may not receive the same updates. If you are starting a new project, use Mendeley Reference Manager. If you are using Mendeley Desktop, verify that your version supports the features you need.

The sync behavior also differs. Mendeley Reference Manager syncs your library across devices. Mendeley Desktop syncs as well, but the two versions do not always sync the same metadata. If you switch between versions, you may see inconsistencies in your tags and collections.

### Create a Tag Vocabulary

Before you begin tagging, create a short list of tags that reflect the likely themes of your review. This list should be based on your research question and your preliminary reading. It does not need to be final. You will revise it as you read.

A useful starting point is to create tags for the following categories:

- Study design: "randomized trial," "cohort study," "case report," "systematic review," "meta-analysis"
- Topic area: "diagnosis," "treatment," "prevention," "epidemiology," "economics"
- Population: "cattle," "swine," "poultry," "companion animal," "human"
- Outcome: "mortality," "morbidity," "cost," "welfare," "resistance"
- Role in your review: "background," "key evidence," "counterargument," "gap"

You do not need to use all of these categories. The point is to have a consistent vocabulary so that you can filter your library reliably.

### Apply Tags Consistently

Consistency is the main challenge in tagging. If you tag one paper as "treatment" and another as "therapy," you will not be able to find both papers with a single search. Decide on a single term for each concept and use it consistently.

You can improve consistency by reviewing your tags periodically. Mendeley Reference Manager shows a list of all tags in your library. Review this list and merge tags that are duplicates or near duplicates. For example, if you have both "treatment" and "therapy," decide which term to keep and apply it to all relevant references.

## Building a Thematic Workflow

### Step 1: Import and Tag as You Read

When you add a reference to your library, tag it immediately. Do not wait until you have a large batch. Tagging at the point of entry ensures that you capture your initial judgment about the paper's relevance. You can refine the tag later, but the initial tag gives you a starting point.

Use the reference's abstract and your own reading to decide on tags. If you have not read the full text, tag based on the abstract and the title. You can add more specific tags after you read the full paper.

### Step 2: Create Smart Collections for Stable Themes

Smart collections are useful for themes that have clear inclusion criteria. For example, if you want a collection of all systematic reviews, create a smart collection that matches the tag "systematic review." If you want a collection of all papers about a specific drug, create a smart collection that matches the drug name in the title or abstract.

Smart collections are also useful for themes that are defined by a combination of criteria. For example, you might want a collection of papers about "treatment failure in cattle." You can create a smart collection that matches the tags "treatment failure" and "cattle."

### Step 3: Use Regular Collections for Fixed Lists

Regular collections are useful when you have a fixed list of references that you want to keep together. For example, you might create a regular collection for the references you plan to cite in a specific section of your review. This collection is a working list, not a thematic grouping.

Regular collections are also useful for references that you have not yet tagged. You can place them in a regular collection as a holding area and tag them later.

### Step 4: Review and Refine Your Themes

Set aside time to review your library and your tags. This review should happen at regular intervals, such as after you have added a certain number of references or after you have completed a draft of your outline.

During the review, ask the following questions:

- Are there tags that are too broad and need to be split?
- Are there tags that are too narrow and need to be merged?
- Are there references that are missing tags?
- Are there references that have tags that no longer reflect their role in your review?

Make the changes you identify. This is the iterative refinement that makes thematic organization work.

## At a Glance

| Organizing Method | Best For | Limitation | Example Use |
| --- | --- | --- | --- |
| Regular folders | Fixed lists, section-by-section citation lists | Forces one location per reference | A folder for "Introduction references" |
| Tags | Assigning multiple concepts to a single reference | No hierarchy, manual renaming | Tag a paper as "treatment" and "cattle" |
| Smart collections | Automatic grouping by criteria | Requires consistent tags or keywords | A collection of all papers tagged "systematic review" |
| Combined approach | Narrative reviews with evolving themes | Requires periodic tag review | Tag all references, then build smart collections |

## Practical Implementation Steps

### Step 1: Audit Your Current Library

Before you reorganize, understand what you have. Open your Mendeley library and review the existing folders and collections. Identify any references that are in multiple folders or that are difficult to find. This audit tells you where your current organization is failing.

If you have a large library, you may want to export a list of your references to a spreadsheet. This gives you a way to review your library without scrolling through the Mendeley interface. You can sort the list by title, author, or year and identify gaps in your coverage.

### Step 2: Define Your Initial Theme List

Based on your research question and your preliminary outline, create a list of themes. This list should be short, perhaps 5 to 10 themes. Each theme should be a concept that will appear in your narrative review.

Write the themes down and keep them visible while you work. You will revise this list as you read, but having a starting point will help you tag consistently.

### Step 3: Tag Your Existing References

Work through your existing library and apply tags to each reference. This is a time-consuming step, but it is necessary. You cannot build a thematic organization without tagging your references.

If you have a large library, you may want to work in batches. Tag all references in one folder, then move to the next. This approach is more manageable than trying to tag the entire library in one session.

### Step 4: Create Smart Collections

After you have tagged a portion of your library, create smart collections for your stable themes. Use the tag names as the criteria for the smart collections. This will automatically group all references that share a theme.

You can also create smart collections based on keywords in the title or abstract. For example, if you have a theme about "antimicrobial resistance," you can create a smart collection that matches the phrase "antimicrobial resistance" in the title or abstract.

### Step 5: Use Regular Collections for Working Lists

Create regular collections for the references you plan to cite in specific sections of your manuscript. These collections are working lists that you can update as you write. They are not thematic organizations, but they help you manage the writing process.

### Step 6: Review and Refine

Set a schedule for reviewing your tags and collections. A weekly review is reasonable during the active reading phase. During the review, check for inconsistent tags, missing tags, and themes that need to be split or merged.

## Records and Measurements

### Track Your Tagging Progress

You can measure your tagging progress by counting the number of references that have at least one tag. Mendeley does not provide a direct count of untagged references, but you can create a smart collection that matches references with no tags. The number of references in that collection is your untagged count.

A reasonable goal is to have every reference in your library tagged. This does not mean every reference needs multiple tags. A reference that is peripheral to your review may have only one tag. The goal is to ensure that you can find any reference by theme.

### Track Your Theme Coverage

You can also track how many references are in each theme. This gives you a sense of the balance of your literature. If one theme has very few references, you may need to search for more literature. If one theme has many references, you may need to narrow your focus.

This measurement is useful for narrative reviews because it helps you identify gaps in the literature. A theme with few references may be a gap that you can discuss in your review.

### Record Your Tag Vocabulary

Keep a record of your tag vocabulary. This can be a simple list in a text file or a spreadsheet. The record should include the tag name and a definition of what it means. This helps you maintain consistency and also helps you onboard a collaborator if you are working in a team.

## Common Failure Patterns

### Inconsistent Tag Vocabulary

The most common failure is inconsistent tagging. You tag one paper as "treatment" and another as "therapy." When you search for "treatment," you miss the paper tagged "therapy." This failure is easy to avoid if you maintain a tag vocabulary and review your tags regularly.

### Overly Broad Tags

Another failure is creating tags that are too broad. A tag like "clinical" may include hundreds of references that are not related to each other. This makes the tag useless for finding a specific theme. If you have a broad tag, split it into more specific tags.

### Overly Narrow Tags

The opposite failure is creating tags that are too narrow. A tag like "bovine respiratory disease in feedlot cattle in the Midwest" may apply to only one or two references. This tag is not useful for grouping. If you have a narrow tag, consider merging it with a broader tag.

### Neglecting to Tag

Some researchers tag only the references they have read and leave the rest untagged. This creates a library where some references are findable and others are not. The solution is to tag every reference as you add it to your library.

### Relying Only on Folders

If you continue to use folders as your primary organization, you will face the problem of references that belong to multiple themes. You will have to choose one folder for each reference, and you will lose the connections between themes. The solution is to use tags and smart collections in addition to folders.

## Limitations of Thematic Organization in Mendeley

### No Tag Hierarchy

Mendeley does not support hierarchical tags. You cannot create a parent tag and child tags. This means you cannot organize your tags into a tree structure. You must use a flat list of tags, which can become unwieldy if you have many tags.

### Manual Tag Renaming

Mendeley does not provide a way to rename a tag across your entire library in one operation. If you decide to change a tag name, you must edit each reference individually. This is time-consuming for a large library. You can avoid this problem by choosing your tag names carefully and reviewing your vocabulary regularly.

### Limited Smart Collection Criteria

Smart collections in Mendeley support a limited set of criteria. You can match on tags, titles, authors, and other fields, but you cannot create complex Boolean queries. This limits the usefulness of smart collections for themes that require nuanced criteria.

### Sync Issues

Mendeley's sync can be inconsistent, especially if you use multiple devices. Tags and collections may not sync immediately, and you may see different versions of your library on different devices. This is a practical limitation that you should be aware of when you work across devices.

## Welfare and Safety Context

Thematic organization is a research management practice, not a clinical or animal welfare practice. However, the quality of your literature organization affects the quality of your review, which in turn affects the decisions that readers make based on your review. A narrative review that misses a key theme may lead readers to make decisions without the full evidence base.

For animal farming topics, this is particularly important. A review about treatment protocols that misses a theme about welfare outcomes may lead readers to choose a treatment that is effective but causes avoidable suffering. A review about management practices that misses a theme about economic costs may lead readers to adopt a practice that is not sustainable.

The [Committee on Publication Ethics](https://publicationethics.org/core-practices) core practices emphasize the importance of accurate and complete reporting. Your thematic organization is part of your research process, and it should support the accurate reporting of the literature.

## Professional Escalation Criteria

If you are working on a narrative review that will be submitted for publication, you should consider the following escalation criteria:

- If you cannot find a theme that you know exists in the literature, you may need to expand your search strategy. This is a signal that your initial search was not comprehensive.
- If you have a theme with very few references, you may need to consider whether the theme is actually supported by the literature. This is a signal that you may need to revise your argument.
- If you are working with a team and you cannot agree on a tag vocabulary, you should stop and create a shared vocabulary before proceeding. This is a signal that your team needs a common framework.
- If you are preparing a grant application, you should ensure that your literature organization supports the [NIH Grants and Funding](https://grants.nih.gov/) requirements for a strong application. A well-organized literature review is part of a strong application.

## Frequently Asked Questions

### How do I create a tag in Mendeley?

Select a reference in your library and find the tag field in the details panel. Type a tag name and press Enter. You can add multiple tags to a single reference. The tag will appear in the tag list for your library.

### Can I use smart collections for themes that require judgment?

Smart collections are based on automatic criteria, so they cannot apply judgment. If a theme requires you to decide whether a reference belongs, you should tag the reference manually and then create a smart collection based on that tag.

### How do I rename a tag in Mendeley?

Mendeley does not have a bulk rename feature for tags. You must edit each reference individually. To avoid this, choose your tag names carefully and review your vocabulary regularly.

### What is the difference between a tag and a collection?

A tag is a property of a reference. A collection is a grouping of references. A reference can have many tags but can only be in one folder. Smart collections are automatic groupings based on criteria, and a reference can be in many smart collections.

### How do I find references that have no tags?

Create a smart collection with a criterion that matches references with no tags. The exact method depends on your version of Mendeley. You can also review your library and sort by the tag field to identify untagged references.

### Can I use Mendeley for a systematic review?

Mendeley can help you organize references for a systematic review, but it is not a systematic review tool. You will need to follow a systematic review protocol and use a tool that supports screening and data extraction. The [EQUATOR Network](https://www.equator-network.org/) provides reporting guidelines for systematic reviews and other study types.

### How do I share my thematic organization with a collaborator?

You can share a collection with a collaborator in Mendeley. The collaborator can see the references in the collection, but they may not see your tags unless you share the entire library. If you are working in a team, you should agree on a tag vocabulary before you start.

### What should I do if my library is too large to tag manually?

If you have a very large library, you may need to prioritize. Tag the references that are most relevant to your review first. You can also use smart collections to group references by keyword, and then tag the references in each smart collection.

## Using the Evidence

| Source | Best use in this topic | Important limitation |
|---|---|---|
| [Research Methods Resources](https://www.ncbi.nlm.nih.gov/books) | official guidance | Check the linked page for current local requirements |
| [EQUATOR Network](https://www.equator-network.org/) | official guidance | Check the linked page for current local requirements |
| [Core Practices](https://publicationethics.org/core-practices) | official guidance | Check the linked page for current local requirements |

## Related Articles

- [Scientific Literature Review: A Reproducible Search and Synthesis Workflow](/blog/careers/scientific-literature-review-a-reproducible-search-and-synthesis-workflow)
- [Scientific Literature Review Format: A Reproducible Structure for Researchers](/blog/careers/scientific-literature-review-format-a-reproducible-structure-for-researchers)
- [Umbrella Reviews: Synthesizing Evidence from Multiple Meta-Analyses](/blog/guides/umbrella-reviews-synthesizing-evidence-from-multiple-meta-analyses)
- [Biological Replicates in RNA-seq: Designing for Inference Rather Than Appearance](/blog/guides/biological-replicates-in-rna-seq-designing-for-inference-rather-than-appearance)
- [organ system definition biology](/blog/guides/organ-system-definition-biology)

## References and Further Reading

- [Research Methods Resources](https://www.ncbi.nlm.nih.gov/books). National Library of Medicine.
- [EQUATOR Network](https://www.equator-network.org/). EQUATOR Network.
- [Core Practices](https://publicationethics.org/core-practices). Committee on Publication Ethics.
- [NIH Grants and Funding](https://grants.nih.gov/). National Institutes of Health.
- [ORCID for Researchers](https://info.orcid.org/researchers). ORCID.
- [Data Management and Sharing Policy](https://sharing.nih.gov/data-management-and-sharing-policy). National Institutes of Health.
- [NCBI Literature Resources](https://www.ncbi.nlm.nih.gov/). National Center for Biotechnology Information.
- [PubMed](https://pubmed.ncbi.nlm.nih.gov/). National Library of Medicine.

> This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.