BACKGROUND: "Option B+" is a World Health Organization-recommended approach to prevent mother-to-child HIV transmission whereby all HIV-positive pregnant and lactating women initiate lifelong antiretroviral therapy (ART). This review of early Option B+ implementation experience is intended to inform Ministries of Health and others involved in implementing Option B+. METHODS: This implementation science study analyzed data from 11 African countries supported by the Elizabeth Glaser Pediatric AIDS Foundation (EGPAF) to describe early experience implementing Option B+. Data are from 4 sources: (1) national guidelines for prevention of mother-to-child HIV transmission and Option B+ implementation plans, (2) aggregated service delivery data between January 2013 and March 2014 from EGPAF-supported sites, (3) field visits to Option B+ implementation sites, and (4) relevant EGPAF research, quality improvement, and evaluation studies. RESULTS: Rapid adoption of Option B+ led to large increases in percentage of HIV-positive pregnant women accessing ART in antenatal care. By the end of 2013, most programs reached at least 50% of HIV-positive women in antenatal care with ART, even in countries using a phased approach to implementation. Scaling up Option B+ through integrating ART in maternal and child health settings has required expansion of the workforce, and task shifting to allow nurse-led ART initiation has created staffing pressure on lower-level cadres for counseling and community follow-up. Complex data collection needs may be impairing data quality. DISCUSSION: Early experiences with Option B+ implementation demonstrate promise. Continued program evaluation is needed, as is specific attention to counseling and support around initiation of lifetime ART in the context of pregnancy and lactation.