Background: Knowing family history is important for understanding cancer risk, yet communication within families is suboptimal. Providing strategies to enhance communication may be useful. Methods: Four hundred ninety women were recruited from urban, safety-net, hospital-based primary care women's health clinics. Participants were randomized to receive the KinFact intervention or the control handout on lowering risks for breast/colon cancer and screening recommendations. Cancer family history was reviewed with all participants. The 20-minute KinFact intervention, based in communication and behavior theory, included reviewing individualized breast/colon cancer risks and an interactive presentation about cancer and communication. Study outcomes included whether participants reported collecting family history, shared cancer risk information with relatives, and the frequency of communication with relatives. Data were collected at baseline, 1, 6, and 14 months. Results: Overall, intervention participants were significantly more likely to gather family cancer information at follow-up (odds ratio [OR]: 2.73; 95% confidence interval [CI]: 2.01, 3.71) and to share familial cancer information with relatives (OR: 1.85; 95% CI: 1.37, 2.48). Communication frequency (1 = not at all; 4 = a lot) was significantly increased at follow-up (1.67 vs. 1.54). Differences were not modified by age, race, education, or family history. However, effects were modified by pregnancy status and genetic literacy. Intervention effects for information gathering and frequency were observed for nonpregnant women but not for pregnant women. Additionally, intervention effects were observed for information gathering in women with high genetic literacy, but not in women with low genetic literacy. Conclusions: The KinFact intervention successfully promoted family communication about cancer risk. Educating women to enhance their communication skills surrounding family history may allow them to partner more effectively with their families and ultimately their providers in discussing risks and prevention.