Whether having children improves our well-being is a long-standing topic of debate. Demographic and sociological research has investigated changes in individuals’ overall well-being and partnership satisfaction when they become parents. However, little is known about how becoming parent may produce vulnerability—observable as an enduring decrease in well-being—in life domains that are strongly interdependent with the family domain, such as work and leisure. Linking life-course and personality psychology perspectives, the authors examine the trajectories of subjective well-being—measured as satisfaction with life, work, and leisure—3 years before and 3 years after the transition to parenthood. The authors particularly focus on the moderating effects of gender and personality. Using data from the German Socio-Economic Panel (1984–2013) and multilevel growth curve modeling, the authors show strong gender-based vulnerability in how people react to parenthood. Although men display a nonlinear pathway of decreasing life satisfaction and a stable trajectory of job satisfaction, women experience more changes in their satisfaction with work and more dramatic decreases in leisure satisfaction. Contrary to most of our expectations, the moderating effects of personality were modest. Extraversion influenced the trajectories of work satisfaction, whereas neuroticism and conscientiousness affected the pathway of leisure satisfaction for women only. This article shows that the transition to parenthood influences well-being trajectories in specific domains, and this influence differs between women and men.