This study examined the efficacy of Albert Ellis' Rational Emotive Behaviour Therapy (REBT) in fostering emotional adjustment among Nigerian adolescents. Fifty senior secondary school students were randomly selected and divided equally into experimental and control groups. The experimental group was treated with REBT twice a week for six weeks. The result indicated that REBT effectively reduced the levels of anxiety and stress of the adolescents. Although the experimental group's level of depression dropped, the reduction was not statistically significant. Implications for counselling the Nigerian adolescents includes using the REBT principles to draw up a treatment programme for treating identified maladjusted adolescents within the classroom and using it to manage the classroom climate in order to facilitate the teaching/learning process.