Identifying individuals with hereditary cancer predisposition can improve health outcomes for patients and their family members through early cancer detection and prevention strategies. Prior research about family sharing of genetic test results among those with hereditary breast cancer has overwhelmingly been limited to the BRCA1 and BRCA2 genes. The present study sought to compare family sharing behaviors in women with pathogenic BRCA variants to women with pathogenic variants in the more recently identified and characterized PALB2 gene. A total of 18 BRCA carriers and 13 PALB2 carriers were interviewed about family sharing practices using a semi-structured guide based on the Integrated Behavioral Model. Barriers and facilitators to family sharing were similar for both BRCA and PALB2 carriers, with logistical difficulties and emotional struggles related to anticipated negative reactions from relatives being the most salient barriers. The most important facilitators were: attitude that sharing enables health protection, provider recommendation, strong family relationships, confidence in sharing basic information, knowledge of what to share and how to share, and belief that sharing is highly important. Given similar attitudes, norms, and control beliefs related to family sharing, similar, but tailored interventions may be effective at increasing family disclosures among both groups. Such interventions should involve a discussion of patients’ attitudes towards sharing with healthcare providers to strengthen motivations and address barriers and provision of informational resources to increase confidence and knowledge. Family sharing resources should clearly specify which relatives need to be informed, why sharing is important, and how at-risk relatives may benefit.