This paper is focused on mother-tongue instruction in Nigerian primary schools, its problems and challenges for the Reading Association of Nigeria (RAN) and educational evaluation. The paper maintains that the state of arts of MT instruction leaves much to be desired. Mother- tongue instruction varies across primary schools and that there are problems of inadequate number of bilingual teachers, poor teacher training, non-development of many of the Nigerian languages, as well as lack of materials for MT instruction. The challenges of these problems for RAN and educational evaluators were highlighted. These include cooperation between RAN and educational evaluators in monitoring the implementation of MT instruction, organization of workshops and seminars for primary school teachers, initiating of enlightenment programs by RAN, and development and validation of instruments for monitoring and evaluation of MT instruction by educational evaluators. It was concluded that if RAN and educational evaluators work together to complement the efforts of the Federal government, the problems of MT instruction will minimize.