Purpose
To determine whether adolescents' normative beliefs about abstinence and condoms, their personal risk perception, and safer sex practices changed after the implementation of a peer sexual health education intervention implemented in Zambian secondary schools.

Methods
The peer intervention was implemented during the first week of September 2000 in Lusaka, Zambia. A quasi-experimental, longitudinal panel design was used to evaluate its impact. Three schools were randomly assigned to the intervention condition and two to the control condition. Three rounds of data from male and female adolescents in grades 10 and 11 were collected at baseline in July 2000, at first follow-up in the second half of September 2000, and at second follow-up in early April 2001. A total of 416 respondents aged 14–23 (at baseline) were interviewed in all three survey rounds. A mixed-effects logistic regression growth curve analysis was used to calculate adjusted odds ratios to compare intervention and control groups on the outcome variables.

Results
Student self-reports showed positive changes in normative beliefs about abstinence immediately after the intervention, and these improvements were largely sustained until 6 months after the intervention. Students became more likely to approve of condom use and to intend using condoms immediately after the intervention, but these positive outcomes could not be sustained during the 6 months that followed the intervention. Normative beliefs regarding condom use took longer to develop: these were only observed at 6 months follow-up. Students reported reductions in multiple regular partnerships. There was no change in condom use.

Conclusions
A single session school-based peer sexual health intervention resulted in the development of normative beliefs about abstinence that were sustained over a 6-month period. Normative beliefs about condoms took longer to develop. More regular efforts may be required to sustain the approval of, and the intention to use, condoms. The intervention was successful in reducing multiple regular partnerships