Capitalization Rules in English: A Guide

Capitalization rules in English are more complex than they first appear. The basic rule is simple: capitalise proper nouns (specific names) and the first word of a sentence. But in academic writing, the edges are blurry. Is “the government” capitalised? Is “internet” capitalised? What about headings, figure captions, and reference list entries? The answers depend on context and style guide.

For non-native English speakers, capitalization is especially confusing because the rules differ between languages. German capitalises all nouns. French does not capitalise days of the week or months. Arabic and many Asian languages do not have upper and lower case at all. If you are writing in English and applying the capitalization conventions of your first language, errors will follow.

This guide covers the capitalization rules that matter most for academic research writing.

The Basic Rule: Proper Nouns vs Common Nouns

Proper nouns (specific names) are capitalised. Common nouns (general categories) are not. “Harvard University” is capitalised because it is the name of a specific institution. “The university” is not capitalised because it refers to universities in general, or to the institution without using its name.

This distinction applies across all categories. People: “Professor Smith” (specific) vs “the professor” (general). Places: “Southeast Asia” (specific region) vs “the southern region” (general). Organisations: “the World Health Organization” (specific) vs “the organisation” (general). Titles of works: “the Journal of Applied Psychology” (specific) vs “the journal” (general).

A common error in academic manuscripts is capitalising general terms that feel important. “The Participants were recruited from three Universities.” Neither “participants” nor “universities” should be capitalised here because they are common nouns, not specific names.

Capitalization in Headings and Titles

Academic writing uses two capitalization styles for headings and titles, and the choice depends on your style guide.

Title case capitalises the first word, the last word, and all major words (nouns, verbs, adjectives, adverbs). Minor words (articles, short prepositions, conjunctions) are not capitalised unless they are the first or last word. “The Effect of Temperature on Enzyme Activity in Tropical Soils.” Chicago Manual of Style uses title case for headings.

Sentence case capitalises only the first word and any proper nouns. “The effect of temperature on enzyme activity in tropical soils.” APA 7th edition uses sentence case for reference list titles and for most headings within the paper (Level 1 headings are bold and title case, but Level 3+ are sentence case).

The most common error is mixing the two styles within a manuscript. If your paper uses sentence case for headings, do not switch to title case for one heading because the topic feels more important. Consistency is the rule.

Academic and Scientific Terms

Most academic and scientific terms are not capitalised. “Quantum mechanics,” “regression analysis,” “cognitive behavioural therapy,” “grounded theory” (as a general method) are all lowercase. They are common nouns describing general concepts.

However, some specific theories, tests, and scales are capitalised when they refer to a particular named entity. “Maslow’s Hierarchy of Needs” (a specific named theory). “The Beck Depression Inventory” (a specific named instrument). “Grounded Theory” (when referring specifically to the methodology as formulated by Glaser and Strauss, though many writers use lowercase even in this case).

Chemical element names are not capitalised (“sodium,” “oxygen”), but their symbols are (“Na,” “O”). Species names follow binomial nomenclature: the genus is capitalised, the species is not, and both are italicised (“Escherichia coli,” abbreviated to “E. coli”).

The safest approach is to check a recent paper in your target journal for how they handle the specific terms you are using.

Days, Months, Languages, and Nationalities

In English, days of the week (Monday, Tuesday) and months (January, February) are always capitalised. This differs from French, Spanish, Portuguese, and many other languages where they are lowercase.

Languages and nationalities are always capitalised in English: “English,” “Chinese,” “Malaysian,” “Arabic.” Adjectives derived from proper nouns are also capitalised: “Bayesian statistics,” “Euclidean geometry,” “Marxist theory.”

Seasons are not capitalised in English unless they are part of a specific title: “the summer of 2023” (lowercase) vs “the Summer 2023 Conference” (capitalised as part of a title).

Acronyms and Abbreviations

Acronyms are written in all capitals: WHO, UNESCO, ANOVA, SEM, GDP. When you spell out the full term on first use, capitalise only if it is a proper noun. “The World Health Organization (WHO)” is capitalised because it is the name of a specific organisation. “Analysis of variance (ANOVA)” is not capitalised because it describes a general statistical method, not a named entity.

For more on abbreviations in academic writing, see our dedicated guide.

Capitalization After a Colon

This rule depends on your style guide. APA capitalises the first word after a colon if what follows is a complete sentence. “The results were clear: The intervention significantly reduced anxiety.” If what follows is not a complete sentence, do not capitalise. “The study examined three variables: age, gender, and education.”

Chicago Manual of Style does not capitalise after a colon unless what follows is a direct quotation or more than one sentence.

The key, again, is consistency within your manuscript.

Conclusion

Capitalization errors in academic writing are rarely catastrophic, but they are noticeable. An editor or reviewer who sees inconsistent capitalization in headings, random capitalisation of common nouns, or mixed title/sentence case in the reference list will question the overall care taken with the manuscript. The rules are straightforward once you learn the distinction between proper and common nouns, and between title case and sentence case. After that, it is a matter of following your style guide consistently.

Want your manuscript checked for consistent formatting and style? PM Proofreading’s journal editing service covers capitalization, punctuation, grammar, and adherence to your target journal’s style guide. Upload your manuscript and get a quote.

Further Reading

• Overall English Grammar Review for Non-Native Researchers
• A Quick Guide to Punctuation for Non-Native Researchers
• All About Abbreviations in Academic Writing: A Guide
• Academic Citations and References: A Complete Guide

Frequently Asked Questions

Should I capitalise discipline names like “biology” or “psychology”?

No. Academic discipline names are common nouns and are not capitalised in English: “biology,” “psychology,” “computer science,” “economics.” They are only capitalised when they are part of a specific department or programme name: “the Department of Psychology at the University of Melbourne.” This is one of the most common capitalization errors in academic manuscripts.

What is the difference between title case and sentence case?

Title case capitalises all major words: “The Effect of Temperature on Enzyme Activity.” Sentence case capitalises only the first word and proper nouns: “The effect of temperature on enzyme activity.” APA uses sentence case for reference list titles and most headings. Chicago uses title case for headings and titles. Check which style your journal uses and apply it consistently.

Should “internet” be capitalised?

No. “Internet” was historically capitalised as a proper noun (referring to the specific global network), but current major style guides (APA 7th edition, AP style, Chicago 17th edition) all use lowercase “internet.” Unless your style guide specifically requires capitalisation, use lowercase.

Do I capitalise “figure” and “table” when referring to them in text?

It depends on your style guide. APA capitalises “Figure” and “Table” when followed by a number: “as shown in Figure 3” and “Table 2 presents the results.” When used generally without a number, they are lowercase: “the figures in this chapter.” Chicago does not capitalise these references. Check your target journal’s convention and apply it consistently.