A condom use promotion leaflet was designed for use with older teenagers in schools. The text targeted a series of cognitive and behavioural antecedents of condom use identified in the literature. Given previous evidence that motivational incentives can enhance the effectiveness of health promotion leaflets, the leaflet was presented in conjunction with a quiz and prize draw. Students were randomly assigned to either the intervention condition or a (no leaflet or incentive) control condition. Measures were taken immediately, pre-intervention and 4 weeks later from 404 students. The 20-min intervention successfully promoted six of the eight measured cognitions, namely (1) attitude towards using condoms with a new partner (2) attitude towards using condoms with a steady partner (3) normative beliefs in relation to preparatory actions (4) self-efficacy in relation to both preparatory actions and (5) condom use (6) intention to use condoms, as well as three measured preparatory actions, that is, purchasing condoms, carrying condoms and discussing condom use. The intervention did not increase condom use with steady or new partners but power to test intervention impact on condom use was curtailed.