From an interview with the editors of Contesting Archives: Finding Women in the Sources (Inside Higher Ed):
[Mary Elizabeth] Perry: When we “contest archives,” we question them, look for more, ask why they are presenting some information but not other kinds of information. …
“Reading against the grain” quite simply means that we read historical records critically, looking especially at the power context in which it was written and the power motivations of those who wrote the document. We contextualize documents as we read them so that we can probe more to learn what the document is not saying and why.