AP Style holds that academic departments should be lowercase unless they are proper nouns or adjectives. For example,
- The department of linguistics; the linguistics department.
- The department of history; the history department.
- The department of science; the science department.
- The department of physics; the physics department.
- The department of economics; the physics department.
- The department of communications; the communications department.
- The department of mathematics; the mathematics department.
-but-
- The department of English; the English.
- The department of American culture; the American culture department.
- The department of Eastern European literature; the Eastern European literature department.
In these latter examples, the capitalized departments are either proper nouns (English) or proper adjectives (American, Eastern European), so AP Style capitalizes them.
You also capitalize the name of an academic department in AP Style if it isthe official and formal name of the department.
For example,
- The University of Michigan Department of Philosophy.
- The Ohio State Department of Economics.