To assess the factors associated with adolescent pregnancies among secondary students at Tanga municipality. A cross sectional descriptive analytical study which targeted all girls in secondary schools at Tanga municipality, Low socioeconomic status was found to be an important cause for adolescent pregnancies as 57.1% of respondents suggested. Other factors responsible were luxury and deprivation of education to girls (43.5% and 16.5% respectively). Source of reproductive health education was contrary to most previous studies as 82.6% reported to get it from parents and health centres, while schools and peer groups contributed only 29.1% and 7.2% respectively. Parents and guardians are important source of reproductive health education to adolescents and useful for prevention of early pregnancies. Early marriages are not as much important as source of adolescent pregnancies. I encourage parents/guardians, to educate their children on reproductive issues, and to increase access to education for girls, which is of paramount importance in preventing adolescent pregnancies.