Background: Young women diagnosed with breast cancer face unique challenges. The desire to have a biologic child (bchild) is often a factor in treatment decisions at diagnosis and follow-up. The aim of this study is to characterize the intentions, attitudes, and decision factors considered by young women who desire to have a bchild after a diagnosis of EBC. Methods: This prospective study included young women diagnosed with stage 1-3 EBC under age 45 who saw an oncologist at UCSF’s Breast Care Center (BCC). Young women < 6 months from diagnosis were invited to complete a baseline REDCap survey on fertility, child-bearing, and family-building. Descriptive statistics were used to summarize responses. Chi square and independent samples t tests were used to compare demographics. Covariates were analyzed using odds ratios. Results: From Feb 2018 to Dec 2020, 166 eligible pts seen at the UCSF BCC were contacted, 143 pts consented, and 108 (75.5%) completed the baseline survey. Of the 108 pts, 57 (53%) were interested in having a bchild in the future. Age was the biggest driver of whether participants were interested in future child-bearing vs. not (Mean = 35.4 vs 40.9, p < 0.001) and was not influenced by stage, receptor status, or treatment. 73.6% (N = 42) of those interested in future child-bearing underwent or planned to undergo fertility preservation (FP). FP was associated with full time employment (p = 0.03) and higher education (p = 0.02). Of the 57 pts interested in future child-bearing (42 HR+, 11 TN, 12 HER2+), 30% wished to start trying to conceive within 2 years from diagnosis, and only 20% would wait 5 years or more. 43% (N = 18) of those with HR+ disease were willing to complete 5 years of hormone therapy (HT) before trying to conceive. Given hypothetical risk scenarios of an incurable cancer recurrence, 16.3% of participants were interested in a future bchild despite a 75-100% hypothetical risk of recurrence (ROR). Young women self-identified as Asian were less inclined to pursue child-bearing with increasing risk (OR = 0.3 vs. Caucasian, p = 0.04), while BRCA-carriers were more likely to remain interested in future child-bearing despite increasing risk (OR = 6.43 vs. non-carriers, p = 0.03). 59% would stop adjuvant HT early if the hypothetical absolute increased ROR from early discontinuation was < 10%. Conclusions: In this single-institution study, over half of young women with EBC expressed a desire to have a future bchild. This was independent of stage, receptor status, and treatment; the majority of women wished to conceive < 5 years from diagnosis. The desire for a future bchild decreased with increasing hypothetical risk of incurable recurrence; however, a subset wished to attempt child-bearing even when an incurable recurrence was certain. Having a bchild after EBC is a priority for many young women and should be addressed at diagnosis and throughout the continuum of care.