Despite significant changes in gender roles and fertility patterns, most women become mothers and this experience shapes their identities and lives in meaningful ways. As important as whether or not women have children, is when they become mothers. Prevalent studies on the timing of the transition to motherhood tend to neglect women’s views and experiences, provide disembedded and binary accounts of time and agency, and disregard an in-depth analysis of time. In this thesis, I draw on conceptual elements from sociology, the life course perspective, and gender and feminist theories to address the ways in which women understand, experience and make the timing of the transition to motherhood in contemporary Chile. This research is framed within a constructivist paradigm, an interpretive epistemology, and a qualitative research design, and is based on life story interviews with 40 women from urban Santiago de Chile. The findings of this thesis reveal that making the right time in the transition to motherhood is shaped by the politics of choice and the multidimensional nature of time. In becoming mothers, women have to resolve cultural contradictions of agency regarding pregnancy and fertility. While neoliberal and postfeminist ideologies outline women as free, equal, and responsible to determine when to have children, in practice, their choices remain constrained by gender norms, restrictions to reproductive agency, and social inequalities. In becoming mothers, women also have to reconcile multiple ontologies of time, conflicting age norms and the sequence of the life course. This involves negotiating the influence of nature and God, the boundaries of the biological clock, the risks of ‘early’ and ‘late’ childbearing, and the delay of motherhood. By challenging binary understandings of the relationship between time and agency, this thesis unveils the complexities and nuances of lived experiences of timing the transition to motherhood, and advances theoretical and empirical knowledge on the intersections between motherhood, time and agency.