Cooperative learning has been increasingly recognized as an effective instructional strategy in English language teaching and learning. However, traditional lecturing still dominates in tertiary education inVietnam, thereby hindering students from actively participating in speaking activities or sharing responsibility for their learning. Also, research into cooperative learning in relation to learner motivation in speaking at high school is scant in the Mekong Delta. This paper therefore reports on a study which examines the effects of using cooperative learning structures to increase learner motivation to speak and investigates their attitudes towards this type of interactive learning. Data collected for this study include a one-group pre-test and post-test design, questionnaires, and interviews with grade ten students at a high school in Vinh Long province. The findings indicate that students were motivated and improved in speaking through cooperative learning after the study. Implications for this interactive learning practice to improve student learning in speaking are also presented.