There is still uncertainty as to whether and in what way parental leave can affect women's fertility, and first and foremost their completed fertility (Bergsvik, Fauske, and Hart 2020; Thévenon and Gauthier 2011). This, impacting the total number of children women have by the end of their reproductive years, may be considered "the ultimate goal of family policies" (Hoem 2008, 250). Specifically, the policy goal in developed countries has generally been to increase completed fertility, as it has been declining for a long time and many developed countries consider their fertility level to be too low (United Nations 2004, 9–10). In order to reduce this knowledge gap, this thesis explores the association between parental leave length and women's completed fertility. More specifically, two research questions are posed: (1) Whether and in what way is parental leave length at the country level associated with women's completed fertility at the individual level? (2) Whether and in what way does the association between parental leave length and completed fertility vary with women's educational level? To answer these questions, I conduct a multilevel analysis with individual-level data from the Harmonized Histories Database and country-level data from the Comparative Family Policy Database. Ten OECD countries are included in the analysis, which focuses on parental leave length schemes in 1991–96 and women of birth cohort 1960–65. For a more nuanced analysis and discussion, two measures of parental leave length are used––income-compensated and total leave length. In line with my research questions, I first analyze the association between parental leave length and women's completed fertility. I find that it has a positive impact that the income-compensated leave length is at its maximum, indicating a generous combination of length and income compensation, and that the total leave length is not too short or too long. Second, I analyze whether the association between parental leave length and completed fertility varies with women's educational level. The results show meager differences. I do not find any educational difference in terms of income-compensated leave length. However, compared to a short and long total leave, I do find an intermediate total leave to have a slightly stronger positive association with lower-educated women's completed fertility. In my discussion of the analysis results, I draw on economic and institutional theory and previous research. Overall, with my contribution, we are one step closer to understanding whether and in what way parental leave is associated with women's final number of children.