The Lesotho education system is largely ineffective, as evidenced by high failure rates in the school-leaving examinations. The situation is linked to ineffective primary education, due to poor teacher quality, weak school management, and a lack of resources, which have carry-over effects on secondary education. Despite these, some secondary schools consistently produce good Grade 12 results. To probe this phenomenon, data was collected through questionnaires from 374 Grade 12 students at 13 high-performing secondary schools. The findings revealed that the main reason for their excellent performance was the stringent selectivity of students in Grade 8, effective school leadership, and teacher efficiency. To improve the effectiveness of Lesotho secondary schools, it is recommended that teacher quality, school management, monitoring, and professional development be intensified aggressively in primary and secondary schools as the two sectors are interlinked.