The issue of exhibitionism among the present day adolescents has become a major source of concern to our many adults in our society, therefore this study examined the efficacy of Assertiveness Training (AT) as a technique that could be adopted to reduce exhibitionism tendency of senior secondary female students in Lagos metropolis. Ninety randomly selected senior secondary school class one constitutes the sample of the study. The study adopted pretest, post- test control group quasi-experimental design with 2x2x2 factorial matrix. Adolescent Exhibitionism Scale (AES) and Adolescent Personal Data Inventory (APDI) Self-Concept Section A were the two instruments employed in the study. Two null hypotheses were formulated and analysed in this study. Data were analysed using Analysis of Covariance and i-test. The findings of the study confirmed the effectiveness of assertiveness training in reducing significantly the exhibitionism tendency of female adolescent students in Lagos. Hence, it is recommended that efforts should be made especially by school counsellors to make use of this technique to curb the problem of adolescents exhibitionism in society.