In this research, effects on grammar and writing achievement of a Turkish language instruction in which a programmed grammar source book followed are explored. Turkish Republic of Northern Cyprus primary schools eighth grade students is the population of this research. The participants of this research are assigned randomly into two groups namely control group (n = 33) and experimental group (n = 30). The experimental group followed a programmed grammar source book in the teaching-learning sessions in Turkish language instruction, whereas the control group followed a grammar book based on traditional methods. Findings of this research revealed that the experimental group students were more successful in grammar compared to the control group students. However, no significant differences were observed between the experimental and the control group students in terms of writing skills.