Teachers’ attitudes toward science teaching influence science teaching and learning. Promoting positive attitudes toward science teaching in pre-service science teachers appears as an important task for science teacher educators. This study aims (a) to explore 113 pre-service science teachers’ attitudes toward science teaching at the beginning of the first semester in a standard-based science teacher preparation program, which had initiated in a university located in the middle region of Thailand, and (b) to track attitude changes of 30 volunteered participants after one semester of participation. The results revealed that, in overall, the participants had positive attitudes toward science teaching both at the beginning and the end of the semester. The participants with different genders significantly had different attitudes toward science teaching both at the beginning and the end of the semester, whereas the class level and study major variables did not significantly yield such differences. After one semester of participation in the standard-based program, the participants did not significantly enhance their attitudes toward science teaching. They, however, expressed additional negative attitudes regarding their inability to teach science adequately. The implications regarding how to promote positive attitudes toward science teaching in the context of science education are drawn from the results.