Girls’ education is one of the most discussed issues in the world. School environment has an influence in promoting girls’ educational needs. Explicit to school environment, is the peril of girls’ pregnancies that this study intended to address. The purpose of this study was to examine the relationship between school environment and girls’ pregnancies in secondary schools in Ilemela District, Tanzania. The study adopted a mixed research method and exploratory sequential design. Study population consisted of 60 O level secondary school girls and boys aged 14-19 years as well as 8 teachers, who filled in questionnaires and were chosen using random sampling. Interviews with key informants in schools and a vocational training centre where focus group discussion was conducted were used in this study. The findings revealed that naivety among students, uncaring teachers, indiscipline among teachers and students, long distances from home to school, poor/lack of transport, temptations from men and poor parents’ involvement in school affairs exposed schoolgirls to the burden of pregnancy. It was recommended that there should be strengthening of counselling departments as well as introduction of sex education in schools so as students can become knowledgeable of reproductive health matters and avoid sexual behaviours. Also, there should be responsibility among teachers and students in fulfilling intended school goals in order to achieve good academic performance and lessen the number of pregnancies and school dropouts.