We investigate the disengagement of four former activists of the Landless Rural Workers Movement (Movimento dos Trabalhadores Rurais Sem Terra—MST) in Brazil. The MST is the largest Brazilian social movement and has mobilized activists for over 30 years. The trajectories of recruitment, participation and disengagement of its activists serve as emblematic cases for the study of disengagement in social movements in general. This research contributes to the understanding of the activists’ disengagement from a social movement, a phenomenon that has been little studied. It sheds new light on the study of disengagement in two ways. First, some characteristics of the MST, in particular that many activists live in tight-knit communities, children participation and the activists’ long-lasting participation, open up new possibilities for the analysis of factors that influence disengagement pointed out in previous studies. In addition, the analysis of former activists’ whole trajectories of recruitment-participation-disengagement allows us show that considering disengagement as the analogous process as recruitment cannot explain all of its aspects. Given that the reasons that make someone leave a movement are, not always, the same that made someone join it. A multiple-case study design was used. The semi-structured interviews encompassing the engagement trajectories of the former activists served very well to the purpose of evidencing the multi-level character of the disengagement decision-making. Our analysis reveals how the social context, the movement and the activists’ personal characteristics in conjunction play a pivotal role.