This article theorizes “omission,” which I define as the condition of being left out of administrative apparatuses, such as civil registers, censuses, and identity management systems. According to this theory, omission is not necessarily accidental but can constitute a political strategy. When even excluded statuses can be powerful grounds for claiming rights, resources, or membership, state actors can subvert such claims-making potential by depriving unwanted populations of the practical, material capacity to establish their legal personhood through documents and records. To situate omission, I develop a typology of documentary strategies additionally comprising “recognition,” “claims-making,” and “evasion.” Although my theorizing is informed by ethnographic research with unregistered families in Malaysia, scholars can apply this typology to multiperspectival, relational analyses of other empirical cases of documentary politics. Studying omissions has scholarly and ethical imperatives, not least to record the lives of populations denied, at times with existential consequences, the right to recognition.