The purpose of this study was to discover whether Twitter could improve the students’ reading comprehension and their written communication in English. The course was designed to extend the students’ reading competence through reading the external links on Twitter and the Twitter activities were to facilitate not only the students’ reading fluency, but also the students’ writing skills by having the learners to engage in the asking and answering questions activities. The results of the average scores progressed greatly from the students’ pretest to the posttest. From the t-test analysis of the participants’ full scores on their both exams, the students’ mean score was 78.04 and SD was 9.226 in their posttest which showed better performance than their pretest. The mean score in their pretest was 60.24 and SD was 7.996. The analysis showed p < .05 which indicated a significant difference. This showed that the majority of the students’ English proficiency had improved in their reading comprehension and writing skills. The writing fluency was evaluated by a number of short-essay questions related to the students’ materials in their textbook. The rubrics of the assessment were based on three principles; relevant to the topics, depth of the idea, and grammatical structure of the sentences. Furthermore, over 95 percent of the students felt that Twitter made a positive impact on their English learning as well as their motivation based on the result in the questionnaire.