The ULINCS Project research describes how elementary teachers learned a model for integrating skills of mathematics, reading, and writing with the teaching of science which led to increased teaching skills and enhanced student achievement. This joint university and school district project was funded by an Eisenhower Grant, and focused on educators working in teams to synthesize curriculum standards while planning and teaching an integrated unit. The evidence indicates that when two or more teachers at a grade level were involved in the ULINCS Project, student achievement across the grade level improved. These experienced elementary teacher participants attained a personal level of self-efficacy, and adopted dispositions that allowed them to work at a comfortable pace when dealing with district and statewide changes. Although all schools and classes in the district evidenced achievement gains, the students in classes taught by the ULINCS teachers evidenced greater gains. The research results document increases in student achievement as well as teachers' personal development. Not surprisingly, there is a direct link between teacher thinking and student performance. The "invisible" thinking skills of teachers help generate new possibilities and increase instructional flexibility. When given a sustained professional development opportunity that challenges their content knowledge and pedagogical thinking, teachers may develop an increased capacity which leads to a high level of professional efficacy.