The purpose of this study was to investigate the effects on achievement and attitude resulting from the use of a calculator-based curriculum and a classroom set of hand-held calculators in ninth-grade general mathematics. Six teachers participated in the study, each having one class in the calculator treatment and one class in the non-calculator treatment. Students in both groups were given pretests in mathematics achievement and attitude. Both treatment groups were given units of instruction on estimation, computation, and problem solving using the four arithmetic operations on whole numbers. The calculator group used a classroom set of hand-held calculators in instruction. The non-calculator group used paper and pencil only. Posttests in mathematics achievement and attitude were given to both groups. Half of each group took the achievement posttest with a hand-held calculator as an aid. The other half of each group took the achievement posttest using paper and pencil only. The resulting data were analyzed using analysis of covariance. Among the findings were that the use of calculator-based curriculum did not significantly affect student achievement in computation or student attitude toward mathematics but did have a positive effect on student achievement in problem solving. (MN)