In this paper, we theorize a bottom-up model of personality and delineate ways in which personality traits can develop and change from the accumulation of daily situations and behaviors over time. We posit that social roles, which represent important classes of situations, could elicit different types of short-term goals. We then argue that these goals can serve as psychological components of situations, thus exerting an influence on personality states, which aggregated over the long-term can shape broad personality traits. We discuss both the long-term processes involved in the transformation of personality traits as a function of roles, as well as the micro-level processes that occur in people’s daily lives, linking social roles, short-term goals, and personality states. Finally, we discuss future directions extending the scope of our model.