The present study examined factors that promote parent-child discussions about sex topics. A sample of 1,066 dyads of African American mothers and their 9-12-year-old children participated completing computer-administered surveys. After controlling for all other covariates, mother's sexual communication responsiveness (i.e., knowledge, comfort, skills, and confidence) was the most consistent predictor of discussions. Mothers with higher responsiveness had significantly increased odds of discussions about abstinence, puberty, and reproduction, based on both mother and child reports. In addition, child's age, pubertal development, readiness to learn about sex, and being female were positively associated with an increase in the odds of discussions in most models. Findings indicate that encouraging parents to talk with their children early may not be sufficient to promote parent-child sex discussions. Parents also need the knowledge, comfort, skills, and confidence to communicate effectively and keep them from avoiding these often difficult and emotional conversations with their children.