This mixed method study reports long-term effects of a staff development model on P-12 teachers' instructional practices and dispositions regarding Internet integration into teaching. The model design was guided by participants' varying professional developmental levels and their values and beliefs about teaching and learning. A survey, administered at three checkpoints over a three-year period, yielded quantitative data regarding participants' concerns about the curricular innovation. Qualitative data, gathered through interviews conducted with a sample of the participants, contributed to understanding, from the participants' perspective, changes they perceived in their teaching practices as a result of the staff development. Elements of the model most instrumental in effecting changes were identified. Results support the recommendation for teacher-centered staff development that includes critical characteristics to effect and sustain change in teacher practice. These features must emanate from teacher practice and be supported by the system in which the teacher works.