The agent-failure model excludes the possibility of attributionally ambiguous but intentional microaggressions, and, by extension, the possibility of covert, microaggressive harassment. By focusing on forms of microaggressive harassment targeting trans women athletes, the authors offer a bi-directional analysis of the role stereotypes play in a perpetrator’s unintentional use of the fundamental attribution error (FAE) by examining this error as a precursor to transmisogynist microaggressive harassment in context of single-gender sports. The FAE, however, reveals a different precursor to microaggressions. In this case, the attribution of aggression to Alison’s gender identity as transgender is a cognitive error based off of a set of sex/gender stereotypes. The relative lack of academic work on microaggressive harassment reflects broader limitations with the agent-failure model. The FAE illuminates just how insidious microaggressive harassment can be. Whether intentional or not, the success of deflecting the blame for committing a microaggression, especially resulting from the FAE, by exploiting the attributional ambiguity of microaggressions dovetails with epistemic gaslighting.