The study sought to investigate the relationships among peer pressure, time management and academic performance of in-school adolescents in Delta-State. In pursuance of the aforementioned objectives, six research questions were posed and one hypothesis postulated. Subjects for the study consisted of 600 in-school adolescents from the three Senatorial Zones in Delta-State. They were composed using random sampling technique. The instrument used for data collection used was a researcher made Questionnaire titled ―Peer Pressure‖ and ―Time Management‖. The data were analysed using mean scores and standard Deviation while the hypothesis was tested at 0.05 level of significance using t-test. The findings show that a higher percentage of in-school adolescents experienced a moderate level of peer pressure and time management. This is followed by a lower percentage of in-school adolescents with love peer pressure as well as time management. However, a significant number of in-school adolescents experienced a high level of time management but not peer pressure. Male in-school adolescents have a high mean ( X ) of peer pressure while female in-school adolescents have low mean ( X ) of peer pressure and time management. Female in-school adolescents performed slightly higher than the male in-school adolescents academically. There is a slight negative relationship between peer pressure and time management. There is a slight negative relationship between peer pressure and academic performance. There is a slight positive relationship between time management and academic performance. There are no significant relationships among levels of peer pressure, time management and academic performance of in-school adolescents. Based on the findings, implications were highlighted and recommendations were made. The recommendations include that that there is a negative relationship between peer pressure and time management of in- school adolescents, and that trained counselors should be posted to all the secondary schools so as to help counsel them on peer influence.