Political scientists have increasingly documented correlations between personality traits, measured using the Ten Item Personality Inventory (TIPI) battery, and Americans’ political attitudes and behaviors. Those correlations are often interpreted as giving causal agency to personality in shaping political outcomes. Such causal claims depend on two key assumptions: personality measurements (1) display stability over time and (2) predate political behaviors of interest. In this article, we employ a new set of empirical tests using new panel survey data to test these assumptions. First, we find only very modest variation in TIPI scores over time. Second, however, we show this variability to be associated in certain cases with political and social variables, which raises serious doubts about the nature of personality as a factor that predates both socio-demographic and—more importantly—political variables. We pay particular attention to openness. While the stability of the TIPI instrument is encouraging, the association between politics and the TIPI instrument suggests that TIPI may vary in response to political events.