This study investigated the effects of SRSD(Self-Regulated Strategy Development) reading and writing instruction on reading comprehension and writing competence for students with mild intellectual disabilities. Participants were three middle school students with mild intellectual disabilities. The experiment used multiple probe design across subjects and was carried out in the order of baseline, intervention and maintenance. Reading evaluation was based on participants’ use of SRSD strategies in reading an expository passage and solving the reading comprehension questions. Writing evaluation was based on participants’ use of SRSD strategies in writing an outline of the reading passage measured both quantitatively and qualitatively. The key findings of the experiment are as follows: (1) reading instruction with SRSD implementation was effective in improving reading comprehension for middles school students with mild intellectual disabilities, (2) SRSD can improve writing abilities for middle school students with mild intellectual disabilities both quantitatively and qualitatively and (3) the effects of intervention were maintained during the maintenance period following two weeks after the intervention. The implications and limitations of the present study are further discussed.