The study probes into the effect of Computer Assisted Instruction and Cognitive preference style on achievement of secondary school Physics Students in Ogun State of Nigeria. The population of the study comprises the SS II students in Abeokuta Educational Zone. 186 students sample were drawn from the population for the study. Two main valid and reliable instruments were used for data collection: Physics Achievement Test (KR20 = 0.83) and Physics Cognitive Preference Style Inventory (KR20 = 0.86). The result revealed significant main effect of treatment [F (1,186) =28.651, P < 0.05 ] and cognitive preference style [F (3,186) =23.349, P