The social significance of sport has surged in recent decades, and promoting sport participation have become a priority in governmental policies and campaigns related to sports, physical activity and health. Nonetheless, sport participation is dynamic and generally decreases during the life course. This dissertation investigated to what extend major life events play a role in this. Particularly, it examined sport participation during the transition into adulthood and the impact of life events that mark this transition. The research findings show that leaving full-time education, beginning work, moving out to live on your own, engaging in a relationship, starting to cohabit or getting married, and becoming a parent affect the likelihood of starting and stopping a sport, the sport participation frequency and setting, and/or the number of sports practiced. So, these major live events are game changers, which sports providers and policy makers, among others, should take into account when promoting “lifelong sport participation” and “sports for all”. Jasper van Houten (1986) obtained his bachelor's degree in health at the HAN University of Applied Sciences in 2008, and subsequently obtained his bachelor's (2010) and master's (2012) degree in Sociology cum laude at the Radboud University. Since 2011 up to today, he works at the HAN School of Sport and Exercise as a lecturer and researcher as well as a senior consultant at the Transferpunt Sport. The studies presented in this dissertation were performed at Radboud Social Cultural Research (RSCR) in collaboration with the HAN University of Applied Sciences.