The purposes of this research were to study English reading and writing abilities of Mathayom Suksa 4 students taught through Cooperative Integrated Reading and Composition (CIRC) technique. The target group was 24 Mathayom Suksa 4/1, Mathematics-Science program, taking Foundation English 2 course (E.31102) at Songkwae Witthayakom School, Chiang Mai Province during the academic year of 2013. The experimental instrument consisted of 6 lesson plans applying Cooperative Integrated Reading and Composition technique. The target group had been taught for 12 weeks. The English reading test and the writing task assessment were administered after each lesson plan. The obtained data were analyzed for mean, standard deviation and percentage. The findings of the study were as follows: 1. The English reading ability of the students did not meet Bureau of Academic Affairs and Educational Standards and Foundation English 2’s criteria after taught through the CIRC technique. 2. The English writing ability of the students met Bureau of Academic Affairs and Educational Standards and Foundation English 2’s criteria after taught through the CIRC technique.