How do the MLA and APA styles differ? The answer lies in why there are different citation styles to begin with. Different citation styles do not compete directly with one another, but are rather designed to bring out the particular elements of a citation reference that are considered most relevant for research in a specific field.

MLA style is used primarily by researchers in the Humanities. MLA style focuses on the author's name, the title of the work quoted, and the particular page number(s) relevant to a citation. The date of publication is not generally considered by scholars in the Humanities to be as significant as it may be in other fields.

APA style is used in particular by researchers in the Social Sciences, with a style that emphasizes the date or timeliness of the publication as well as the author name and page number(s).

Social Science research is often more closely linked to recent developments than Humanities research in the aesthetics of poetry or the nature of semicolons. Thus it follows that publication dates would be emphasized more in APA than in MLA style. There are also separate style guides for Medicine, Biology, Chemistry and other fields that emphasize details of more importance to their research.

How Specifically do MLA and APA Differ?

Both the MLA and APA recommend acknowledging sources via brief parenthetical citations within one's text to an alphabetical list of works (called Works Cited for MLA, and References for APA) that will appear at the end of one's paper. Both styles also allow for numbered endnotes, but as explanatory notes by the author rather than as the traditional footnote/endnote form used in past decades.

Typical of MLA style is the parenthetical citation that concludes the following sentence:

Ancient writers attributed the invention of the monochord to Pythagoras, who lived in the sixth century BC (Marcuse 197).

The citation "(Marcuse 197)" tells readers that the information in the sentence was taken from page 197 of a work by an author named Marcuse. If readers want more information about this source, they can turn to the Works Cited listing, where under the name of Marcuse they would find the following information:

Marcuse, Sibyl. A Survey of Musical Instruments. New York: Harper, 1975.

This entry states that the works' author is Sibyl Marcuse and its title is A Survey of Musical Instruments. The remaining detail indicates that the work was published in New York City by Harper and Row publishers in 1975.

A citation in MLA style contains only enough information to enable readers to find the source in the Works Cited list. If the author's name is mentioned in the text, only the page number appears in the citation: "(197)." If more than one work by the author is in the list of Works Cited, a shortened version of the title is given: "(Marcuse, Survey 197)."

However, in the sciences, where timeliness of research is crucial, the date of publication is given prominence. Thus an APA citation includes the publication date. It also includes the abbreviation p. before page number(s). Compare these APA and MLA citations for the same source:

APA
(Marcuse, 1975, p. 197)

MLA
(Marcuse 197)

In the Humanities, where scholarly research usually remains relevant for a substantial period, publication dates receive less attention. They are always included in the Works Cited listings, but omitted from in-text citations. An additional benefit as seen by many Humanities scholars is that texts have fewer "disruptions" and are thus more easily readable.

In the APA References listing, the date (in parentheses) immediately follows the name of the author (whose first name is given only as an initial), just the first word of the title is capitalized, and the publisher's full name is provided. Also, opposite from MLA style, the first line of the References entry is indented; a second and subsequent lines are flush with the left margin:

APA

      Marcuse, S. (1975). A survey of musical instruments.
New York: Harper and Row.

By contrast, in MLA style the author's name appears as given in the work (normally in full), every important word of the title is capitalized, the publisher's name is shortened, and the publication date is placed at the end. In MLA style the first line of the Works Cited entry is flush with the left margin, and second and subsequent lines are indented. This format helps readers locate authors' names in the alphebetical listing.

MLA

Marcuse, Sibyl.  A Survey of Musical Instruments.
      New York: Harper, 1975.

Examples and some text in the above was taken from (114-16)
Gibaldi, Joseph. MLA Handbook for Writers of Research Papers. Fifth edition. New York: MLA, 1999.