Many studies in the literature have addressed reading comprehension, the ultimate goal of the reading process, due to its complex nature. These studies have focused on various areas, such as the nature of reading comprehension, how it occurs, the factors that affect the process of comprehension, reading comprehension impediments, and how to improve reading comprehension. The current study aims at examining the cognitive and motivational factors to explain reading comprehension. In the light of the related literature, the cognitive factors in this study were vocabulary, prior knowledge, and use of reading strategies, while the motivational factors include motivation and self-efficacy. Both informative and narrative texts were used to measure the success in reading comprehension. The participants were composed of 384 students studying in 6th grade (F: 205, M: 179). The study results reveal that cognitive and motivational factors predict reading comprehension at a statistically significant level. The most effective two factors are vocabulary and prior knowledge, both of which are cognitive factors. The order of relative importance of the variables is vocabulary, prior knowledge, motivation, self-efficacy, and reading strategies. There are some suggestions made in the light of the study results for researchers and practitioners.