The purpose of this study is to investigate the influence of the web-aided cooperative learning environment on biology preservice teachers' motivation and on their self-efficacy beliefs in biology teaching. The study was carried out with 30 biology preservice teachers attending a state university in Turkey. In the study, the pretest-posttest research design without any control group was used. As the data collection tools, a motivation scale and a self-efficacy belief scale for biology teaching were used. The data collection tools were applied as pretest and posttest on group. During the analysis of the obtained data, paired simples t-test was used. The findings obtained demonstrated that the motivation levels of the biology preservice teachers trained in the Web-Aided Cooperative Learning Environment (WACLE) increased and that there was no significant difference regarding their self-efficacy beliefs in biology teaching. The results were discussed in the light of the literature, and related suggestions were put forward accordingly.