This study investigated the effect of teacher involvement in the development of calculator mathematics curriculum on the implementation of calculators in the classroom. Forty-five middle school mathematics teachers served as subjects. Findings revealed that teachers involved in curriculum development were observed significantly more often than those not involved in curriculum development to: explain the relationship between calculator and paper-and-pencil algorithm, stress the use of the calculator as a "time-saver," stress use of the calculator as a problem-solving tool, and initiate use of calculators in the classroom. Neither teacher attitude nor teacher involvement affected the overall quantity of student calculator use. In classrooms of teachers who were involved in curriculum development, students were observed more often than students in classes of other teachers to use calculators for exploration and induction activities, solving routine word problems, and self-checking and verifying answers. Findings indicate that classroom calculator implementation differences are not primarily the result of teacher attitude toward calculators. (Contains 17 references.) (JDD)