Amid rising concerns about climate change, in recent years, demographers have increasingly examined whether environmental concerns have become a factor in shaping reproductive intentions and outcomes. However, little is still known about the potentially reciprocal relationship between environmental concerns and fertility, in part due to the lack of longitudinal analyses of sufficient temporal scope. Our study provides new results based on unique data from the German Socio-Economic Panel (GSOEP), which contains both full fertility histories and yearly (1984 to 2020) measurements of environmental concern. We follow individuals born between 1965 and 2000 and investigate (a) whether environmental concerns predict first-birth quantum and timing and (b) whether environmental concern trajectories vary between eventual parents and the childless. Overall, results indicate no significant link between environmental concerns—whether early in life or across the life course—and (the timing of) the transition to parenthood, or the number of children achieved by age 40. However, we find a negative association between environmental concerns and the chances of becoming a parent for older birth cohorts, suggesting a potential generational shift in how ecological awareness intersects with fertility decisions. Moreover, parents seem to be more worried about the environment than the childless, though these differences seem to be largely explained by unobserved heterogeneity rather than parenthood itself.