Orphaned adolescents are a large and vulnerable population in sub-Saharan Africa, at higher risk for HIV than non-orphans. Yet prevention of new infection is critical for adolescents since they are less likely than adults to enter and remain in treatment, and are the only age group with rising AIDS death rates. We report process evaluation for a randomized controlled trial (RCT) testing support to stay in school (tuition, uniform, nurse visits) as an HIV-prevention strategy for orphaned Kenyan adolescents. The RCT found no intervention effect on HIV/HSV-2 biomarker outcomes. With process evaluation, we examined the extent to which intervention elements were implemented as intended among the intervention group (N=412) over the 3-year study period (2012–2014), the implementation effects on school enrollment (0–9 terms), and whether more time in school impacted HIV/HSV-2. All analyses examined differences as a whole, and by gender. Findings indicate that school fees and uniforms were fully implemented in 94% and 96% of cases, respectively. On average, participants received 79% of the required nurse visits. Although better implementation of nurse visits predicted more terms in school, number of terms did not predict the likelihood of HIV/HSV-2 infection. Attending boarding school also increased number of school terms, but reduced the odds of infection for boys only. Four previous RCTs have been conducted in sub-Saharan Africa and only one found limited evidence of school impact on adolescent HIV/HSV-2 infection. Our findings add further indication that the association between school support and HIV/HSV-2 prevention appears to be weak or under-specified.