Unintended pregnancy is an individual and public health problem with significant social and economic consequences. The literature has established that parents, especially mothers, play an important role in shaping the contraceptive attitudes and behaviors of young women and could therefore affect the likelihood of their daughter experiencing an unintended pregnancy. However, research has yet to fully explore the nuances of how mothers influence their daughters with respect to contraception.We conducted a mixed methods study to explore the impact of mothers on women's contraceptive attitudes and behaviors. In-depth interviews were conducted with 86 women of reproductive age to identify potential patterns and explore the nature of mothers' influences. We then analyzed medical and prescription claims for a cohort of 9813 pairs of women (mother-daughter proxies) enrolled in Medicaid, to determine if such patterns of contraceptive use held in a larger sample.In-depth interviews reveal how and why mothers shape women's contraceptive attitudes and behaviors, particularly highlighting the nuances of communication, knowledge, and relationships. The statistical claims data supported such findings on a broader scale. For instance, across several types of contraceptives, including oral, injectable, and long-acting reversible contraceptives (LARCs), young women were significantly more likely to use a particular method if an older woman in the household (mother proxy) also used that method (AOR (95% CI) 1.99 (1.67-2.37), 2.06 (1.58-2.68) and 2.83 (1.64-4.88) respectively).This study fills a gap in the literature regarding the nuanced ways in which mothers influence women's contraceptive behavior. In turn, it supports the importance of familial context-especially the influence of mothers-in contraception decision-making and suggests that interventions aimed at improving access to and uptake of effective methods of contraception consider this context in their design and implementation.