The integration of technology in teaching is still challenging for most teachers, even though there has been a historical growth of Internet access and available educational technology tools in schools. Teachers have not incorporated technology into their teaching for various reasons, such as lack of knowledge of technology, time, and support. In this study, three beginning science teachers who successfully achieved technology integration were followed for 3 years to investigate how their beliefs, knowledge, and identity contributed to their uses of technology in their classroom instruction. The findings demonstrate that the participating teachers were all intrinsically motivated to use technology in their teaching and this motivation allowed them to enjoy using technology in their instruction and kept them engaged in technology use. The major findings of the study are displayed in a model, which indicates that the internalization of the technology use comes from reflection and that teachers' use of technology in classroom instruction is constructed jointly by their technology, pedagogy, and content knowledge; beliefs; identity; and the resources that are available to them. The study has implications for teachers and teacher educators for successful technology integration into science classrooms. (Contains 1 figure.)