Locus of control, a psychological construct, has been the focus of attention in recent decades. Psychologists have discussed the effect of locus of control on achieving life goals in social/psychological interactions. While learning a foreign language involves both social interactions and psychological processes, the role and relation of locus of control in foreign language achievement is seemingly overlooked. This study is, therefore, concerned with examining the relationship between EFL learners' locus of control (LOC) and their L2 reading and writing achievement. Using Internal Control Index as the main instrument of the study and measuring L2 reading and writing achievements of 136 undergraduate students studying English as their major in two universities followed by an interview, the researchers examined the relation of their locus of control and their writing and reading comprehension achievements. The results of the study indicated that locus of control had a positive correlation with their L2 reading and writing achievement. Also the results of the interviews supported the information obtained from the questionnaires. The researchers have pinpointed to the importance of inculcating a sense of responsibility in EFL learners to improve their LOC orientation which might result in higher achievements in L2 reading and writing.