Dissertation (MSc Nursing Education)Background: It is estimated that almost 6% of female and 9% of males have experienced abuse in Zanzibar before 18th year of their birthday. Child sexual abuse and health risk issues among adolescents are alarming and have been reported in a wider extents. This study aims to determine the effect of life skills based training on (LSBT) improving knowledge, attitude and assertive behavior for the prevention of sexual abuse among secondary school adolescents of Pemba Island in Zanzibar Tanzania. Method: A quantitative approach coupled with quasi-experimental pre-post design with control was utilized, a total of 174 treatment and 322 control were selected. Multistage (six) sampling design was used to select proportion of representatives from each school. Stratified sampling was applied in treatment and control as well as random sampling by a lottery method. Data were collected using structured questionnaires whereby frequency and percentage were used in descriptive statistics, chi-square, paired t-tes were used to compare groups, difference in difference was used to determine the effect of intervention on the outcome variable and linear regression was used to dertmine the influence of training in controlling other factors. Results: A total of 522 secondary school adolescent were enrolled in the study, the mean age was 16yrs, mini 13yrs and maxi 18yrs. Findings of the study revealed that LSBT has led increase in knowledge, attitude and assertive behavior by 28.14%, this was 21.65% before the intervention and 49.79% after the intervention. The paired test showed significant difference between pre and post intervention, whereby knowledge score pre intervention was (n=170, M=7.70, SD=3.93) and (n=174, M=14.8, SD=6.48) at post intervention (p=0.01), while attitude score at pre intervention was (n=170, M=8.7, SD=3.93) and (n=174, M=11.0, SD=7.4) at post intervention (p=0001), and behavior score was (n=170, M=7.70, SD=3.93) at pre intervention and (n=174, M=14.8, SD=7.48) at post intervention (p=0.01). Conclusion: Knowledge, attitude and assertive behavior was generally poor before the educational intervention. However, there was a significant change in adolescents‟ knowledge and assertive behavior on sexual abuse prevention after an intervention; thus, life skills intervention is effective in the preferment of sexual abuse prevention knowledge among secondary school adolescents.