TWO STUDIES were conducted to evaluate a comprehensive cooperative learning approach to elementary reading and writing instruction: Cooperative Integrated Reading and Composition (CIRC). In CIRC, thirdand fourth-grade students worked in heterogeneous learning teams for all reading, language arts, and writing activities. In reading, students worked with partners during follow-up times on partner reading, decoding, story structure, prediction, and story summary activities related to the basal stories. Students also received direct instruction on comprehension and metacomprehension activities, followed by team practice. In writing and language arts, students used a process approach to writing, and participated in peer conferences during planning, revising, and editing stages of the process. Students also received direct instruction followed by team practice on language mechanics and language expression activities, which were integrated with the students' writing activities. The authors found significant effects in favor of the CIRC students on standardized measures of reading comprehension, reading vocabulary, language mechanics, language expression, and spelling. The CIRC students also performed better on writing sample and oral reading measures.