This document discusses effective supervision of instruction in Nigerian secondary schools and issues related to quality assurance. It defines supervision and its purposes, who supervisors are, and qualities of effective supervisors. Key impediments to effective supervision are identified as inadequate resources, lack of training and incentives for supervisors, and non-implementation of supervision recommendations. The document concludes that quality assurance in instruction requires effective supervision and addresses recommendations such as using experienced teachers as supervisors and providing supervisors with incentives and resources to do their work.