Background: Family history-based risk assessment for hereditary breast and ovarian cancer and Lynch syndrome is guideline recommended and has strong evidence supporting its implementation into clinical practice, especially primary care. Yet, adoption has been impeded by limited awareness of genetic evaluation guidelines among primary care providers (PCPs), time constraints in screening during appointments, and limited resources for follow-up within primary care. To close this gap, we implemented a hereditary cancer risk assessment program that addresses these barriers and evaluated proximal implementation outcomes. Methods: We used intervention mapping for adaptation (IM-Adapt), a modified version of Intervention Mapping to guide the adaptation and implementation of the evidence-based 7-question family history screening (FHS-7) at a primary care clinic within an academic medical center. FHS-7 was adapted for administration via electronic patient portal prior to PCP visit or in-person at PCP visit. All clinic patients were offered screening and follow-up genetic counseling and testing per guidelines. Administrative, programmatic, and electronic medical record data were analyzed for program evaluation. Results: Between February 2023 and March 2024, 4,540 primary care patients were offered hereditary cancer risk assessment and 3,497 (77%) completed screening. Patient portals were used to complete screening more frequently than in-person at the clinic (86.6% vs 13.4%). Among patients with qualifying family history of cancer (n=1,267, 36%), 1,117 (88%) were eligible for navigation as they completed their primary care appointment and did not undergo genetic counseling within the last 5 years. Of the eligible patients, 62% were successfully contacted by a navigator and offered genetic counseling. Program implementation was facilitated by key personnel (clinical champion, informatics staff, genetic patient navigator) and adaptations to fit the implementation setting (adapting FHS7 for patient self-report rather than administration by PCP, patient population with high patient-portal adoption rate and in-house genetic service resources). Conclusions: We demonstrate the feasibility of hereditary cancer risk assessment within primary care and describe actionable aspects of the implementation context that influence screening uptake that can be incorporated into the design of future implementation for maximum impact. Findings advance the state of science in identification of unaffected individuals with inherited cancer susceptibility and genetic service delivery.