This study attempts to find the factors affecting the development of course materials and its availability, how these determine students’ academic performance in National Open University of Nigeria (NOUN). The study examines whether there are enough course writers/developers for programmes offered. Research questions are raised and hypotheses formulated to guide the study. The instrument used for data collection was the questionnaire, administered on the sampled students from five (5) schools in two study centres in Ogun (Abeokuta) and Oyo (Ibadan) states. Descriptive tables, simple percentages, five points Likert scale are used. Chi-square test is also adopted in the analysis. The major findings of the study are that there are enough course writers / developers for the various programmes offered by NOUN, and there is timely release of fund to enhance printing and transportation of course materials for its availability to students among others. These adequate provisions enhance better reading culture in students which positively affect their academic performances in NOUN. The study concluded that even though the university is doing well, it needs more experienced/ qualified course writers/developers to enhance more quality production of course materials for all old and new programmes offered at NOUN.