Abstract Background: A family history of breast cancer may impact reproductive choices and decisions about family-building. This study evaluated family-building considerations, plans, and decisional processes among women with a breast cancer family history, and examined sociodemographic, clinical, and psychosocial factors related to decision uncertainty. Methods: Cross-sectional data from the Breast Cancer Family Registry (BCFR) Young Women’s Study were analyzed. Participants were women (18-45 years old) with a breast cancer family history. They completed questionnaires including a Reproductive Choices module. Bivariate analyses and multiple regression evaluated relationships among study variables. Results: Participants (N=471) were on average 30.3 years old (SD=6.7), predominantly non-Hispanic White (75.1%), and over half were childless (58.6%); nearly half (47.8%) desired future children, 16.6% were unsure, and 35.7% did not. Among those interested/unsure (n=303), most considered natural conception (85.8%); many were unsure about alternative options such as embryo genetic testing, donor gametes, surrogacy, and adoption. Between 43–57% endorsed some degree of decision uncertainty. Perceived knowledge about genetic cancer risk and family-building options appeared low overall. In the final model, greater decision uncertainty was associated with having no history of pregnancy, identifying as Ashkenazi Jewish, endorsing concern about a future child's health, lack of concern about family-building timeline, and lower perceived knowledge about genetic cancer risk and family-building options. Conclusions: Among women with a familial risk for breast cancer, decision uncertainty about family-building options is prevalent and is driven by health-related concerns, knowledge gaps, financial barriers, and values-based considerations. Findings can inform targeted decision support interventions for this population.