BACKGROUND The academic performance of higher secondary school students plays a crucial role in deciding about next stage of education and career. They belong to middle and late adolescence. Depression is the number one cause of illness and disability in this age group. The adolescents those who are affected with depression early in life often suffer from depression throughout their lives. Adolescents who are depressed have an increase in suicidal tendency and are at higher risk of anxiety, conduct disorders, substance abuse and poor academic achievement. The study intends to identify the prevalence of depression and associated factors. The aim of this study is to estimate the prevalence of depression among higher secondary school students and to identify the factors associated with depression. MATERIALS AND METHODS A cross-sectional study was conducted among 640 adolescents studying in classes XI and XII in higher secondary schools in Taliparamba Taluk, Kannur District, Kerala. In the first stage, students were administered a pretested semi-structured questionnaire (for associated factors) and Patient Health Questionnaire PHQ-9 (for screening). Those students who were found positive were interviewed using the Hamilton's Rating Scale for Depression (HAM-D). Statistical measures like Chi-square test and Fisher's exact test were analysed using SPSS version 16. RESULTS The prevalence of depression was found to be 20.6%. Majority of the students had mild depression (12.8%). Depression was found to be more among males (21.5%) compared to females (19.4%). Factors like age, class of study, father's educational status, neglect, physical abuse, failure in exams, death of parents/ relatives, conflict in the family, poor communication, parental rejection, peer rejection, family history of depression, having someone to discuss worries with, career and university disagreement between the student and the parent were significantly associated with depression. CONCLUSION This study highlights the common but ignored problem of depression in adolescence. Early screening should be instituted in schools by adequately trained counsellors. Teachers, parents, healthcare workers and primary care providers should be trained to identify depression at early stage.