A core proposition of public service motivation (PSM) theory is that PSM is positively related to individual performance. Some studies, however, suggest that this relationship is mediated by person-job or person-organization fit. This study aims to further clarify the relationship between PSM and performance by, first, studying the mediation role of both person-job and person-organization fits and, second, by investigating this mediation for both in-role and extra-role behavior. Whereas in-role behavior is aimed at the individual task, extra-role is aimed at helping colleagues. This difference may matter for the role of PSM and fit. To this end, we conducted structural equation modeling with bootstrapping on self-reported survey data from public employees (n = 1,031). The analysis showed that person-job, but not person-organization fit, fully mediated the relationship between PSM and in-role behavior. The relationship with extra-role behavior was not mediated. The PSM-performance relationship may thus be more complex than previously envisioned, as both type of performance and person-job fit matter.