RESUMEN
The study explores the perceived causes of change in sexual risk behaviour among Nigerian adolescents over the past years. By embedding the results into a theoretical context, the study aims to further develop interventions targeting adolescent sexual health. To do so, 23 semi-structured interviews are conducted through the mobile-instant-messaging tool WhatsApp. The interview sample consists of both female and male adolescents and adults from different regions in Nigeria. The interviews are conducted as simultaneous chats and analysed based on the qualitative content analysis approach. Respondents perceive a multitude of different factors as causes of change in sexual risk behaviour among Nigerian adolescents. They can be categorised into (1) individual actors, (2) structural factors, and (3) socio-cultural factors. Interrelations between the different factors can partly be observed. The other factors are mostly modifiable and can therefore contribute to reducing adolescent SRB.