Although research has shown that self-efficacy beliefs predict academic achievement across all academic subjects and levels, little is known about the effect of using spreadsheets on self-efficacy beliefs in mathematics. This study is an investigation of the effect of instruction that includes spreadsheet-based purposeful activities on secondary school students' self-efficacy beliefs for algebra. The context of the study is a 10th grade mathematics course in a public secondary school. Analysis of the data indicated that students who received spread-sheet-based instruction had significantly higher self-efficacy for algebra than those who received conventional instruction. (Contains 5 tables.)