The study assessed the level of peer pressure among junior secondary school students of Social Studies in Mushin Local Government Area, Lagos State. It also determined the difference between male and female junior secondary school students of Social Studies peer pressure influence on their academic performance and examined the difference across age groups peer pressure influence on academic performance of junior secondary school students in Social Studies in the study area. The study adopted a descriptive survey research design. The target population is the junior secondary school students in Mushin Local Government Areas of Lagos state, Nigeria. Eight junior secondary schools were selected using simple random sampling technique. From each of the schools, thirty students were selected using simple random sampling technique summing up to 240 students that made up the sample for the study. Two self-designed research instruments were used for the study namely: Peer Pressure Questionnaire (PPQ) and Social Studies Test (SST). Data collected were analyzed using frequency, simple percentage, graph and multivariate analysis of variance (MANOVA). The results of the study showed that the students demonstrated moderate peer pressure influence in junior secondary schools, 148(61.7%). The results of the study further indicated that there was no statistically significant difference between male and females on the combined dependent variables (F(2,237) = 0.97, p > 0.05). The results of the findings finally revealed that there was no statistically significant difference between different age groups on the combined dependent variables in the study area (F(2,236) = 0.65, p > 0.05). The study therefore concluded that the level of peer pressure among junior secondary school students is moderate and that the peer pressure influenced their academic performance though moderating variables have no significant influence on the students’ performance in Social Studies in the study area.