This study assessed the longitudinal relationship between perceived fit (i.e., person–organization fit, person–job fit) and affect-based variables (i.e., job satisfaction, negative affect, positive affect) using momentary (i.e., within-person level) and stable (i.e., between-person level) assessments of both sets of variables. In doing so, we tested 3 theoretical models of the perceived fit and work affect relationship (i.e., fit preceding affect; affect preceding fit; reciprocal fit–affect relations) to determine (a) the antecedents and consequences of fit perceptions, (b) whether fit perceptions exhibit meaningful within-person variability, and (c) if direct fit perceptions are simply the result of affect/job satisfaction at work or can influence such work experiences. In addition, we examined whether the relationships between affect/job satisfaction and fit perceptions were homologous (i.e., similar) across the 2 levels of analysis (i.e., within-person and between-person). Results indicated that fit primarily preceded affect and job satisfaction at both levels of analysis, though some specific relationships exhibited reciprocal causality and others supported affect as an antecedent of fit perceptions. Our findings paint a complex picture of the causal relationship between perceived fit and work affect.