By 2010 there will be close to two million orphans in South Africa, mainly as a result of HIV/AIDS. This paper assesses different approaches to the care and support of children orphaned by AIDS and other vulnerable children, as well as the cost-effectiveness of each approach. Using a typology of care and essential elements of care, six approaches are evaluated: informal, non-statutory foster care; community-based support; home-based care; unregistered residential care; statutory adoption and fostering; and statutory residential care. A cost-effectiveness analysis assessed actual programs and the costs of providing a minimum standard of care for the six approaches. High costs are associated with formal models of care. Informal approaches may lack the resources to meet children's rights. Resources should be largely allocated to the more cost-effective, informal, community-based structures, but formal models will still be needed for those children who cannot be placed elsewhere.