The aim of this study was to investigate a behavior of students during cooperative learning about computer programming and its influence on learning performance. Students' opinions and perceptions toward proposed learning activity and a web-based programming assisted system for cooperation (WPASC) were also investigated. Theresults of this study revealed most of students perceived the learning activity and the WPASC were useful for cooperative learning about programming. Students' learning behavior was classified into six categories and it influenced learning performance. Students from completely independent, self-improving using assistance, confident after enlightenment and imitating categories performed well due to effective and motivated learning behavior. Students from performing poorly without assistanceand plagiarizing categories performed the worse; most students could not get assistance due to their low learning motivation. The results also showed that learningbehavior may have increasing, decreasing and no transition. Therefore students of performing poorly without assistance and plagiarizing categories and with decreasing or no transition in learning behavior should be identified at the early stage of the course. Then the instructor should intervene into learning behavior of these students to change it into more effective for learning, give more incentive to increase motivation and also encourage all students to post solutions and feedback at theearly stage of problem solving process.