This research paper explores pre-service science teachers' understandings of classroom research, problems in conducting classroom research and the supports that pre-service science teachers need from their cooperating teachers to help them conduct a classroom research project during the internship period. The participants in this study are 19 pre-service science teachers in a teacher education institution situated in Western Thailand. The research instruments included a questionnaire about the understanding of classroom research and interviews with the pre-service science teachers regarding the problems in conducting a classroom research project and the supports that they need from their cooperating teachers in conducting the classroom research project. The data were analysed using descriptive statistics and content analysis. The results indicate that most of the pre-service science teachers understood the principles of classroom research. The problems the pre-service science teachers encountered in conducting classroom research were the limitation of time, generating suitable research question and selecting the innovation to solve the problem. Pre-service science teachers would like recommendations from their cooperating teachers more frequently for promoting the pre-service science teachers' confidence and efficiency in their chosen classroom research projects. This study has direct implications for the ways in which we introduce and engage pre-service science teachers into inquiry-oriented practice in their chosen profession. A questionnaire and an interview protocol are appended. [This research was funded by the Kasetsart University Graduate School.]