Currently language learning is being facilitated by social networks and microblogging, which emerged as a quite new form of communication and content sharing through which users can publish online some small pieces of digital content. This relates to connectivism, a learning theory that views learning as the process of creating connections and expanding or increasing network complexity. While writing, EFL student teachers at Assiut University Faculty of Education always presented content that was full of redundancy and excessive elaboration. In addition, they demonstrated poor critical reading skills necessary for giving clear and comprehensive summaries of the linguistic content encountered online. Therefore, the present study aims at investigating the effect of microblogging through Twitter on developing those student teachers' critical reading and summarization skills. To accomplish this aim, a review of literature was made supported with some open interviews with EFL specialists to come out with a list of those critical reading skills (3 main skills and 18 sub-skills) and another list of those summarization skills (4 main skills and 24 sub-skills) needed by EFL student teachers. Accordingly, a pre-test on those skills was administered to a group of 50 EFL student teachers (research participants). Then, a microblogging model based on Twitter was experimented with participants for 5 weeks. Finally, a post-test on critical reading and summarization skills was administered to participants, and the means of scores were compared. Results indicated statistically significant differences between the participants' means of scores in both the pre and post-administration of the two tests, and thus microblogging through Twitter was found to be effective in developing EFL student teachers' critical reading and summarization skills. Based on these results, many suggestions and recommendations were presented.