This study assesses the extensiveness of continuous assessment practices in improving students' academic performance in public secondary schools in Monduli District, Tanzania. The study employed a convergent design and mixed-methods research approach guided by the Social Learning Theory by Albert Bandura (1977). The target population in this study includes 12 public secondary schools, 12 heads of schools, 399 teachers, 1823 students, and 1 DSEO. The study sample size comprised 253 respondents, of which 40 teachers were sampled through the stratified random sampling technique; 208 students were selected using the stratified random technique; 4 heads of schools and 1 DSEO were purposively sampled (total population sampling technique) based on the virtue of their position. A questionnaire, interview guide, and document analysis schedule were used to collect the required information. The validity of quantitative instruments was achieved by two research experts in the area of educational assessment and evaluation from Mwenge Catholic University. The reliability of the questionnaires was estimated by Cronbach Alpha technique of which the output was 0.799 which means the instrument was reliable for data collection. The trustworthiness of the qualitative data was ensured by the triangulation of instruments and peer debriefing methods. Quantitative data was analysed using descriptive statistics and presented in tables with the aid of Statistical Package for Social Science (SPSS) version 23. Qualitative data were analysed thematically and presented in words by verbatim quotations. The study found that continuous assessment was practised to a high extent to improve students' academic performance in Monduli District. The study concluded that continuous assessment practices have successively achieved their goal of improving students' academic performance in national examinations to a high extent. The study recommended that there should be monitoring and evaluation of the effectiveness of continuous assessment practices regularly to identify areas for improvement and ensure they continue to be effective in improving student academic performance.