In this chapter, we examine whether commitment affects participants' worldviews. Worldviews, or meanings, 1 are defined as thinking-feeling tools individuals use to make sense of their social and political environment (Mead 1934; Weber 1978). In the present study, participants are those individuals who join an environmental protection organization, a charitable organization, or a union. Evidence in the literature on biographical consequences of activism is supportive (e.g., Passy and Monsch forthcoming; Giugni 2004): Individuals who join an organization synchronize their worldviews with the cultural scripts that circulate in the community. For example, Blee (2016) shows that women who join far-right organizations experience a critical transformation indebted to a radical shift in their interpersonal network. As one of her interviewee's states: "I made new friends and started to become obsessed with race….I thought about race 24/7" (p.9). Commitment therefore affects people's meanings. Yet, a conflicting argument exists in the literature, one that stresses a reverse causality, that is to say, specific worldviews are required to belong to the so-called mobilization potential eventually leading the individual to engage in joint action (e.g., Cotgrove and Duff 1980; Gamson et al. 1982; Kriesi 1989; Klandermans 1997). With this logic in mind, individuals solely join political or civic organizations if their meanings correspond. Commitment, then, does not change worldviews. Our present contribution aims to shed light on this debate by analyzing the effects of joining a political or civic organization on worldviews over time. 1 In this contribution, we use the terms "worldviews" and "meanings" interchangeably.