The online encyclopedia Wikipedia is a frequently referred-to source of information for Internet users. A series of 3 studies examined Wikipedia's coverage of psychology-related concepts, examined how accessible Wikipedia's psychology content is when using Internet search engines, and described how both first-year and senior undergraduates use Wikipedia. The results demonstrated that Wikipedia's coverage of psychological topics was comprehensive and prominently displayed on the major search engines. In addition, a majority of undergraduate students reported referring to Wikipedia for both personal and school-related activities; however, few students reported using Wikipedia as a formal reference in academic work. (Contains 2 tables and 2 notes.)