With millions in need of HIV antiretroviral therapy (ART) in the developing world, and scarce human and fiscal resources available, we conducted a formative evaluation of scale-up operations at clinics associated with AIDS Healthcare Foundation in Africa to identify lessons learned for improving scale-up efficiency. Site visits were made to six selected clinics in Uganda, Zambia, and South Africa, during which semistructured interviews with key stake-holders and observation of client flows and clinic operations were performed. This evaluation revealed the following lessons related to factors that are critical to efficient ART scale-up: (1) to ensure steady ART uptake, it is important to involve the community and community leaders in outreach, HIV education, and program decision-making; (2) minimizing bottlenecks to smooth patient flow requires efficient staff allocation to appropriate clinical duties, streamlined clinic visit schedule protocols, and tapping clients and the HIV community as a key source of labor; (3) to minimize clients dropping out of care, structures should be developed that enable clients to provide support and a "safety net" for helping each other remain in care; (4) computerized record management systems are essential for accurate antiretroviral inventory and dispensing records, quality assurance monitoring, and client enrollment records and visit scheduling; (5) effective organizational management and human resource policies are essential to maintain high job performance and satisfaction and limit burnout; (6) to maximize impact on social and economic health, it is important for ART programs to develop effective mechanisms for coordinating and referring clients to support service organizations.