The introduction of School based Assessments in Zambia were aimed at improving the teaching and learning as well as raise the bar of students performance in the country. However, the implementation of SBA in secondary schools faces unique challenges, particularly in the context of Zambia, exacerbated by the global COVID-19 pandemic. This study investigated the implementation of SBA in science subjects within selected Zambian schools, aiming to develop an evidence-based framework for sustaining the quality delivery of SBA in science education. Through a comprehensive investigation, this research examined the alignment of SBA practices with guidelines and identified gaps in implementation processes. Key objectives included assessing the evaluation of SBA policy since its rollout, examining administration processes, identifying challenges faced by stakeholders, and proposing interventions for improvement. Methodologically, the study employed tools such as questionnaires, interviews, and Focus Group Discussions to collect data. Qualitative data was analysed thematically while quantitative data was analysed using SPSS tool. Research findings revealed that teachers perceived SBA as a process of enhancing teaching and learning of science through the conduct of experiments which in turn improved teachers’ capacity and confidence in handling practical lessons. SBA provided teachers with an opportunity to closely monitor learners’ strengths and weaknesses as well as checking progress of learning. However, a considerable number of teachers held that SBA was an additional load onto their already burdened schedules but mandated to implement it as it was policy. Low staffing levels, time allocated to each science period, the number of tasks, inadequate laboratories and apparatus, resource constraints, high levels of enrolment resulting from positive response of Free Education Policy, many classes to teach by one teacher and lack of motivation, dominated the challenges faced by teachers in SBA implementation. The categorization of SBA revealed a duty-bound approach towards SBA (symbolic compliance), as SBA marks were mandatory for totalling learners’ final marks at the end of secondary school level. The study's recommendations aimed to enhance SBA implementation and foster positive educational outcomes. Furthermore, suggestions for future research include exploring the long-term impact of SBAs on academic performance, conducting comparative studies across different subjects, investigating technology integration, and exploring stakeholder perspectives. The research has contributed valuable insights to the discourse on educational assessment practices, providing a foundation for informed decision-making and strategic actions to improve science education in Zambian schools and beyond.