The study attempted to investigate the effect of explicit morphology instruction (EMI) on developing secondary school students’ EFL morphological awareness and reading comprehension. The explicit morphology instruction targeted two morphological skills namely, inflectional and derivational skills. The study used a pre-posttest experimental and control group design. The intact study participants were (98) first year secondary school students. While the first intact group (n=49) was functioned as an experimental group, the second intact group (n=49) represented the control group. To collect the data, a two-unit explicit morphology instruction program (EMIP), a morphological awareness test (MAT) and a reading comprehension test (RCT) were designed, validated and implemented. Before the intervention, the participants’ morphological awareness and reading comprehension were pre-tested. During the course of intervention, while the experimental group participants were exposed to explicit morphological instruction in addition to their regular English instruction sessions, the participants of the control group only received their regular EFL instruction sessions. Results revealed that the experimental group participants’ mean scores on the post morphological awareness test and reading comprehension test surpassed that of the control group. Accordingly, explicit morphological instruction was effective in developing EFL secondary school students’ morphological awareness and reading comprehension. However, the effect size of explicit morphological instruction on developing EFL secondary school students’ morphological awareness was higher than its effect size on developing their reading comprehension. Therefore, teaching English morphology should be an integral part of EFL secondary school curriculum.