This study was conducted to investigate the effectiveness of using explicit instruction versus incidental learning in enhancing lexical collocational knowledge among third-year English majors at the Faculty of Foreign Languages and Translation, Misr University for Science and Technology. For the purposes of this study, 60 students were divided into two experimental (i.e. explicit instruction and incidental learning) and one control group. A lexical collocation test which consists of two parts, namely, receptive and productive, and a writing quality test were administered for three groups after the treatment. A 10-session treatment was administered for the experimental groups' students, while the control group students followed their regular method. Results revealed a clear advantage for explicit instruction as the explicit instruction group significantly outperformed the incidental learning group and the control group both in receptive and productive lexical knowledge. Results also indicated that the explicit instruction group students outperformed both the incidental and the control groups in the quality of writing. The incidental learning group also reflected some collocation gains with better performance than the control group.