The documentation styles developed by the Modern Language Association and the American Psychological Association reflect divergent assumptions regarding the apprehension and communication of knowledge. Each system expresses its rhetorical character through the aims it articulates, the sources it values, and the formats it prescribes for in-text citations and bibliographic references. Like other scholarly writing conventions, documentation styles are not arbitrary, but both shape and are shaped by the discourse communities that they serve. Emerging scholars need to be acculturated purposively to the conventions of their respective communities, while authors should consciously select bibliographic systems that support their rhetorical aims.