A literature review gives a detailed summary and analysis of published research about a specific topic. It shows where the research agrees, where it disagrees, and where more research is needed. A literature review relies on synthesis.

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Essential guidance

 

What is synthesis?

Synthesis means showing how sources compare to each other, rather than describing them one by one.

When you describe sources one by one, you move through them separately without comparing what they say (Example 1). Synthesised writing organises sources by what they say about the same issue. It shows where they agree and disagree, and builds your position from what the evidence shows (Example 2).

Example

Latip et al. (2013) explained that palm oil expansion damages biodiversity and wildlife habitats.1 Mertz et al. (2013) found that farmers producing palm oil chose greater wealth and income despite the accelerated loss of biodiversity.2 Stigler et al. (2026) find that corporate zero-deforestation commitments achieved high compliance but no additional reduction in deforestation.3

 

Key

  1. Argument of first source Back to text, note 1
  2. Argument of second source Back to text, note 2
  3. Argument of third source Back to text, note 3

 

The sources are presented separately. There is no comparison between them and the writer hasn't used them to help build their argument.

Example

Latip et al. (2013) and Mertz et al. (2013) agree that palm oil expansion causes loss of biodiversity, but they disagree on how to address it.1 Latip et al. (2013) suggested that more community involvement in forest management could protect biodiversity. However, Mertz et al. (2013) found that economic incentives drive local farmers toward producing palm oil no matter the environmental damage.2 Stigler et al. (2026) support this view, finding that even legal zero-deforestation commitments are ineffective beyond the reductions that were already occurring for other reasons.3

 

Key

  1. Outline what the sources agree and disagree on Back to text, note 1
  2. Explain the disagreement in more detail Back to text, note 2
  3. Presents a third source to move the debate forward Back to text, note 3

 

This version of the text builds a position from the evidence rather than describing sources one by one.

Latip, N. A., Badarulzaman, N., Marzuki, A., & Umar, M. U. (2013). Sustainable forest management in Lower Kinabatangan, Sabah: Issues and current practices. Planning Malaysia: Journal of the Malaysian Institute of Planners, 11(3), 59–84. https://doi.org/10.21837/pm.v11i3.108

Mertz, O., Egay, K., Bruun, T. B., & Colding, T. S. (2013). The last swiddens of Sarawak, Malaysia. Human Ecology, 41(1), 109–118. https://doi.org/10.1007/s10745-012-9559-3

Stigler, M., Grabs, J., Heilmayr, R., Carlson, K. M., Chandra, A., Benedict, J. J., & Garrett, R. D. (2026). Zero-deforestation commitments in Indonesia's palm oil sector achieve high compliance but no additionality. Proceedings of the National Academy of Sciences, 123(29), e2511503123. https://doi.org/10.1073/pnas.2511503123

 

The referencing style used here is APA 7. Your course may require a different referencing system. Check your assignment brief or module guidance to confirm which style applies to you.

 

 

How to write your review

Writing a literature review involves two kinds of work: evaluating each source, then organising by theme.

 

Evaluating sources

Before you can write about sources together, you need to understand each one individually. This is the same process you'd apply when reading critically. For each source, consider and make notes about:

  • what claims it makes
  • what evidence it uses
  • whether its methods are sound
  • what its limitations are

 

This is preparation for writing, not a section of the finished review. For help deciding which sources to include, go to Finding and choosing sources.

 

Organising by theme

Organise your review by theme, not by source. A theme is an issue or debate that appears across several of your sources. Each section or paragraph addresses one of these themes and draws on multiple sources. Before you write, a reading grid can help you identify how your sources relate to each theme.

 

As you work across your sources, look for:

  • where researchers agree and where they don't
  • differences in methods or sample sizes between studies
  • differences in research context — for example, whether studies focused on different countries, time periods, or groups of people
  • gaps — aspects of the topic that haven't been studied, or studied only in limited contexts
  • outdated findings that more recent research has challenged or replaced

 

 

What markers are looking for

A strong literature review shows that you understand your subject, can evaluate evidence, and can explain clearly what is and isn't known. It shows where your work fits within existing research.

 

 

What to aim for

A strong literature review is organised by theme. Each section focuses on one theme and combines what different sources say about it. The review evaluates sources, commenting on their strength and relevance. It also paraphrases rather than relying on direct quotations and stays focused on the topic or task throughout.

This is different from an annotated bibliography, which reviews sources individually instead of synthesising across them.

 

 

Advanced guidance

This guidance assumes you have read the essential guidance and focuses on developing a position — your own judgement about what the literature shows and where its evidence is limited. It also explains the importance of identifying knowledge gaps in the literature.

 

What a position looks like

A position isn't a personal opinion. It's a judgement grounded in evidence. You should make this judgement by working carefully across the literature. It shouldn’t be formed until you’ve done most of your planned reading.

A literature review that just describes what sources say is only a starting point. A strong review uses sources to build an argument.

 

 

Organising around a position

The essential guidance recommends organising by theme. That's the right starting point as thematic organisation works well for many positions.

However, some positions depend on showing how thinking on a topic has changed over time, or on showing that different research methods produce different results.

In those cases, a chronological or methodological structure may serve your argument better.

 

Thematic Chronological Methodological

Groups sources by topic or concept.

 

Use this when focusing on how different aspects of a topic relate to each other.

Shows how thinking on a topic has developed over time.

 

Use this when focusing on how understanding has shifted, or how earlier assumptions have been challenged.

Groups sources by the research methods they use.

 

Use this when focusing on how different methods produce different findings, or how certain methods have limitations relevant to your topic.

 

Each of these approaches works independently. Nonetheless, as you progress, you may find that combining them lets you build a stronger position.

 

 

Using the reading grid

A reading grid can map your sources against the themes of your review. At an advanced level, it becomes a tool for developing your position, not just planning your structure.

As you fill the grid, your position should start to become clear. Look for:

  • columns that are thin or empty — these are potential gaps
  • sources that appear across many columns — these are likely central to your position
  • cells where sources contradict each other — these are your synthesis opportunities

 

Some patterns only become visible when you compare all your sources together. If studies using one method tend to arrive at one broad conclusion, and studies using another method tend to arrive at a different one, the method may be shaping the result.

The same is true of context. If studies reach different findings depending on where or when they were done, that difference may matter for your position.

 

 

More complex synthesis

The essential guidance introduced the idea of synthesis. In practice, it's often more complex.

 

Partial agreement

Sources can partially agree in different ways. For example, they may agree on findings but disagree on what they mean, or agree on a problem but disagree on its cause. Identifying exactly where agreement between sources ends is more analytical than simply labelling sources as agreeing or disagreeing (Example 3).

Example

Latip et al. (2013) and Mertz et al. (2013) agree that palm oil expansion causes loss of biodiversity, but they disagree on how to address it.1 Latip et al. (2013) suggested that more community involvement in forest management could protect biodiversity. However, Mertz et al. (2013) found that economic incentives drive local farmers toward producing palm oil no matter the environmental damage.2

 

Key

  1. Outline what the sources agree and disagree on Back to text, note 1
  2. Explain the disagreement in more detail Back to text, note 2

 

References

Latip, N. A., Badarulzaman, N., Marzuki, A., & Umar, M. U. (2013). Sustainable forest management in Lower Kinabatangan, Sabah: Issues and current practices. Planning Malaysia: Journal of the Malaysian Institute of Planners, 11(3), 59–84. https://doi.org/10.21837/pm.v11i3.108

Mertz, O., Egay, K., Bruun, T. B., & Colding, T. S. (2013). The last swiddens of Sarawak, Malaysia. Human Ecology, 41(1), 109–118. https://doi.org/10.1007/s10745-012-9559-3

 

The referencing style used here is APA 7. Your course may require a different referencing system. Check your assignment brief or module guidance to confirm which style applies to you.

 

 

Integrating methodological critique

When writing stronger reviews, you don't evaluate sources separately and then synthesise them. Instead, you comment on a source's methods at the same time you are discussing its findings.

Peer-reviewed studies usually tell you about the limitations of their methods – why you should be cautious of their results. However, there may also be times you find further limitations the authors haven't discussed (Example 4).

See Reading critically for more guidance on this.

Example

Millard et al. (2021) find that more intensive land use reduces pollinator numbers most sharply in tropical regions.1 They note that most of the studies they reviewed came from a small number of countries, which means the findings may not apply everywhere.2 The study also only looks at land use, so it cannot tell us how other pressures, such as pesticides or disease, combine with habitat loss to affect pollinators.3

 

Key

  1. Outline the source's finding Back to text, note 1
  2. Explain the limitation mentioned by the authors Back to text, note 2
  3. Explain further limitations you have found (if any) Back to text, note 3

 

References

Millard, J., Outhwaite, C. L., Kinnersley, R., Freeman, R., Gregory, R. D., Adedoja, O., Gavini, S., Kioko, E., Kuhlmann, M., Ollerton, J., Ren, Z.-X., & Newbold, T. (2021). Global effects of land-use intensity on local pollinator biodiversity. Nature Communications, 12, 2902. https://doi.org/10.1038/s41467-021-23228-3

 

The referencing style used here is APA 7. Your course may require a different referencing system. Check your assignment brief or module guidance to confirm which style applies to you.

 

 

Identifying and framing gaps

A gap is an aspect of a topic the existing literature hasn't fully examined. Identifying gaps is one of the strongest ways to establish a position because they show not just what is known but what remains unresolved.

However, be careful. Overstating a gap weakens your position. Don't claim there is less literature than there actually is. Before claiming a gap, make sure your search of the literature has been thorough. A gap you haven't found is not necessarily a gap that doesn't exist.

A knowledge gap doesn't have to be huge to be important, but it does need to be specific. Instead of broad claims that more research is needed, find exactly what is missing and why it matters for your topic, for example:

  • an understudied group or context
  • a question the literature raises but doesn't answer
  • a methodological limitation that affects the reliability of existing findings
  • a recent development that existing research hasn't addressed

 

Here's the difference between a vague and a precise gap claim:

 

Vague: 'More research is needed on palm oil certification.'

Precise: 'Existing studies focus on deforestation rates but don't examine the long-term economic impact on farming communities.'

 

 

Page last edited: 25 August 2026
Next review due: 13 August 2029