Early modern women marked their books in a variety of ways that provide evidence for their book ownership and use, their reading practices, their facility in arithmetic, writing, and drawing, their acquisition of literacy and education, and their social, political, and religious milieux. They also annotated manuscript materials, returning to their own and others’ scribal writing with corrections, comments, and emendations. Consisting of tens of thousands of unique examples, marginalia form a new and significant corpus of early modern women’s writing that has attracted growing critical attention over the last two decades, forming part of the material turn in literary studies. Analysis of early modern women’s marginalia has moved from case studies of individual women, books, and repositories to more recent considerations of larger literary categories and aggregated small data sets. At both the micro- and macro-historical levels, marginalia provide new ways of understanding early modern women’s relationship to their books and manuscripts as readers, writers, and book users. They raise complex methodological questions about provenance, access, and attribution that contribute to wider debates about how we define and interpret early modern women’s textual engagements.