Do you use brackets the same way you use parentheses?

This page reflects guidance from the sixth edition of the Publication Manual.

For the most current guidelines, see the Publication Manual of the American Psychological Association (7th ed.) and our Style and Grammar Guidelines page for the seventh edition.

Use brackets

to enclose the values that are the limits of a confidence interval.

  • Example:
    95% CIs [-7.2, 4.3], [9.2, 12.4], and [-1.2, -0.5]

to enclose parenthetical material that is already within parentheses.

  • Example:
    (The results for the control group [n = 8] are also presented in Figure 2.)

to enclose material inserted in a quotation by some person other than the original writer.

  • Example:
    "when [his own and others'] behaviors were studied" (Hanisch, 1992, p. 24)

to include nonroutine information in a reference

  • Example:
    Van Nuys, D. (Producer). (2007, December 19). Shrink rap radio [Audio podcast].
         Retrieved from http://www.shrinkrapradio.com

Exceptions

Exception 1: Do not use brackets if the material can be set off easily with commas without confounding meaning:

  • Correct: (as Imai, 1990, later concluded)
  • Incorrect: (as Imai [1990] later concluded)

Exception 2: In mathematical material, the placement of brackets and parentheses is reversed; that is, parentheses appear within brackets.

(adapted from the sixth edition of the APA Publication Manual, © 2010)