The aim of this study was to examine the roles of the School Based Assessments in selected secondary schools in Lusaka district. The study was guided by the three research objectives which were to determine the role of school assessments on learner performance in secondary schools, to establish the effects of school assessments on learner performance and to determine the factors to be considered in the conducting of school local assessments effectively in secondary schools. The study employed the quantitative research approach. Thus data was gathered using questionnaires. The sample size for the study was 309 respondents. Quantitative data was analysed using SPSS version 20 to generate descriptive statistics in the form frequency tables and percentage distributions in order to give clear presentation and interpretation of the research results. The study showed that School Based Assessments helps in skills and concept retention, prepare learners for exams, help identify learners’ weaknesses, teachers evaluate learner’ understanding, wide coverage of reading, expose learners to variety of questions, ensure qualitative scores and help diagnose learners weaknesses. The SBAs have positive effects on the academic performance of learners. Thus they enable learners work extra hard and improve learners’ academic performance with a high retention of skills and concepts. Thus when assessing the learners the following should be considered: age of learners, grade of learners, abilities of learners, level of understanding, strength /weaknesses of learners, school resources, readiness of learners, time, work covered and environment/classroom.