Adolescence is a stage which entails transition in the physical, emotional, and cognitive human development, happening before the onset of puberty and ending by adulthood. This study established adolescent learner behaviour problems in high schools in a developing country. The main focus of this study was on the nature of behaviour problems and their manifestations in the Kingdom of Eswatini. The study established the perceptions five head teachers from five selected schools within the Manzini region. The study employed a qualitative approach and a cased study research design in which face-to-face interviews were used to collect data. The conclusions were drawn. The main conclusions of the study were that high school heads have encountered learners’ behaviour problems amongst the adolescents in high schools. The study also concluded that learner behaviour problems amongst adolescents in high schools come in different forms and are in most noticeable to other members of the school community. The study recommended that counselling could be done to rectify behaviour problems, parents could also be engaged, positive discipline, productive punishment, putting in place effective disciplinary measures, introducing life orientation programs, introduction of health clubs and peer educators.

Keywords : Adolescence, Behaviour, Problems, Manifestations, High Schools