The purpose of this research was to describe how self-efficacy affects the development and science achievement of practicing teachers after their participation in a half day long hands-on science lesson provided by the Science on Wheels project. The 42 practicing K-8 teachers were from eight different counties located in a rural mid-eastern state. A novel survey was created to determine the science achievement and self-efficacy level of the teachers (Bandura, 1995). The survey had 30 questions and the questions were modified from existing surveys in the area of science achievement and self-efficacy. The survey was administered at the beginning of the hands-on science lesson and at the end of the half day long lesson. The hands-on science lesson the inservice teachers participated in was designed for middle school students and dealt with the topics of "Matter" and "Light." The middle school students and the inservice teachers participated in the hands-on science lessons which were part of the "Science on Wheels" program. The data from the surveys were analyzed using a paired t-test to determine differences in the pretest and posttest data. The pretest and posttest data had numerous significant findings. The inservice teachers reported that after they participated in the hands-on science lessons, they felt significantly more confident that they could plan a constructivist/inquiry science lessons [t(41)=4.47<.01]. The teachers also felt they could serve as a resource person [t(41)=4.50<.01] and perform science demonstrations in front of large groups [t(40)=4.32<.01] of people. The last significant finding dealt with a person's ability to tutor another person. The inservice teachers felt more confident that they could tutor a fellow teacher in science [t(40)=3.90<.01]. (Contains 17 references.) (Author/MM)