We love to help students become stronger and more confident academic writers! This list includes the Top 5 areas in which we find the most APA errors in academic writing:


Space once after a period at the end of a sentence and other punctuation, not twice.

  • The APA manual encourages writers to space twice after punctuation marks at the end of a sentence to assist readers of draft manuscripts. Due to advances in technology and word processing software, one space after a period is standard practice for all forms of academic and professional communication.
  • You can easily correct this by searching for two spaces and replacing two spaces with one!

Please see sections 4.01 and 4.02 for a complete overview of guidelines on spacing after punctuation marks and use of periods.


Refer to these quick tips to correct for common errors in commas, colons, and semicolons.

  • A comma (the Oxford comma) should be inserted prior to the conjunction between elements in a series of three or more items. This also applies to a series of three or more authors in an in-text or parenthetical citation.
  • In a series of items, when there are internal commas within any of the individual items, a semicolon should be used to separate the distinct items in the series.
  • A comma should set nonessential or nonrestrictive clauses apart from the sentence. A nonessential or nonrestrictive clauses adds to a sentence but, if removed, would leave the structure of the sentence and its meaning intact. Commas should not be used before an essential or restrictive clause or between two parts of a compound predicate.
  • A comma should be used to separate two independent clauses joined by a conjunction. When two independent clauses are joined by a comma but without a conjunction, an error known as a “comma splice” has been made. Use a semicolon instead of a comma to separate two independent clauses.
  • Use a colon between an introductory clause that is grammatically complete and a secondary or concluding clause that extends on the preceding thought. The first letter of the word that follows the colon should be capitalized if clause following the colon is a complete sentence.
  • Commas (and periods) should be placed inside single and double quotation marks, not outside, unless a parenthetical citation follows the quoted material.

Please see sections 4.03-4.05 for a complete overview of guidelines on commas, semicolons, and colons. See section 4.07 for a complete overview of guidelines on quotation marks.


Refer to these quick tips to correct for common errors in capitalization.

  • The first word in a complete sentence should be capitalized. The first word after a colon that begins a complete sentence should also be capitalized.
  • In the text of the paper, major words in titles of books and articles should be capitalized. This does not include articles, conjunctions, and short prepositions. All words of four letters or more should be capitalized in titles and headings.
  • In titles and headings, capitalize all verbs, linking verbs, nouns, adjectives, adverbs, and pronouns. Both words in a hyphenated compound should also be capitalized in titles and headings, as well as the first word after a colon or dash.
  • In the reference list, only the first word of book or article titles should be capitalized, including the first word after a colon or em dash. Proper nouns in titles should be capitalized.
  • Major words in Heading Level 1 and 2 headings should be capitalized. In Heading Levels 3, 4, and 5, only the first word and any proper nouns should be capitalized.
  • The names of laws, models, theories, frameworks, methodologies, statistical procedures, or hypotheses should not be capitalized.
  • Nouns followed by numerals or letters that denote a specific place in a numbered series should be capitalized (e.g., Table 2, Chapter 3, Appendix A).

Please see sections 4.14-4.20 for a complete overview of guidelines on capitalization.


Numerals should be used to express numbers 10 and above.

  • This includes percentages (25%); numbers that precede units of measurement (4-year degree); numbers that represent time (12:34 a.m.), dates (May 12, 2017), ages (5 years old or 5-year-olds), scores and points on a scale (scored 5 on a 7-point scale), exact sums of money ($1,500.00), ordinal numbers (ninth grader, 10th grader), and numerals as numerals (the number 5); and numbers that denote a specific place in a numbered series (Grade 8), parts of books and tables (Chapter 1, Table 2), and each number in a list of four or more numbers (row 5).

Words should be used to express numbers below 10.

  • This includes any number that begins a sentence, title, or heading; common fractions (one third); and universally accepted usage (The Four Agreements).

Please see sections 4.31-4.38 for a complete overview of guidelines on numbers.


Refer to these quick tips to correct for common errors in quoting and paraphrasing text within a thesis, dissertation, or manuscript.

  • The work of any individual or group of individuals whose ideas, theories, or research have directly influenced your work should be cited appropriately.
  • A source must be credited whether a writer is paraphrasing, quoting an author directly, or describing an idea. Make sure to take careful notes as you research to avoid unintentional plagiarism of someone else’s work.
  • The author, year, and a page (p.) or paragraph (para.) number should be included for any direct quote from a source, and the source should be included in the reference list.
  • Quotes under 40 words should be incorporated into the text; any quote 40 or more words should be set apart from the text as a block quotation, which is indented 1/2 inch from the left-hand margin. Double quotation marks are removed from block quotations, and the parenthetical citation follows the closing punctuation mark. Quoted material within a block quotation should be enclosed in double quotation marks.
  • Parenthetical material should follow directly after a direct quote that appears mid-sentence, rather than at the end of the sentence.
  • If a direct quote is included at the end of a sentence, include the closing period after the parenthetical material, not inside the double quotation marks.
  • APA encourages writers to include a page or paragraph number for paraphrased materials, but this is not required.

Please see sections 6.03-6.10 for a complete overview of guidelines on quoting and paraphrasing.

NOTE: Our Top 5 list was adapted from the guidelines published in the 6th edition of the Publication Manual of the American Psychological Association (2010).


Learn more about WHAT WE DO!