In 2012, there were an estimated 2 million children in need of antiretroviral therapy (ART) in the world, but ART is still reaching fewer than 3 in 10 children in need of treatment. [1, 7] As more HIV-infected children are identified early and universal treatment is initiated in children under 5 regardless of CD4, the success of pediatric HIV programs will depend on our ability to link children into care and treatment programs, and retain them in those services over time. In this review, we summarize key individual, institutional, and systems barriers to diagnosing children with HIV, linking them to care and treatment, and reducing loss to follow-up (LTFU). We also explore how linkage and retention can be optimally measured so as to maximize the impact of available pediatric HIV care and treatment services.