Microaggression is a term used to describe the offhand, casual, fleeting degradation of marginalized people. Microaggressions can occur via an offhand remark, a glance, or a gesture. They suggest that in a world where more explicit forms of discrimination have been made illegal, racist ideology is still carried out via interactions that are so small as to be nearly unnoticeable by anyone other than marginalized group. One of the major themes of Citizen is the impact of these microaggressions on black people and how they connect to larger systems of racism.

Often, the text discusses these microaggressions in a level, detached tone. Writing in The New York Times Sunday Book Review, poet Holly Bass suggests that in doing so, Rankine “creates an intentionally disorienting experience, one that mirrors the experience of racial micro-aggressions her subjects encounter” (Bass, Holly. “Claudia Rankine's 'Citizen'.” The New York Times, The New York Times, 24 Dec. 2014.) Yet the text also explores the physical and emotional consequences of microaggressions and how their accumulation affects the spiritual and physical health of black Americans.