Macintosh computers are being used as tools for active investigation in two different and innovative courses: MULTIVARIABLE CALCULUS AND MATHEMATlCA for upper division mathematics majors and MODELING AND THE SCIENTIFIC METHOD (using STELLA II software) for freshman and sophomore non- science majors. Students use computers to gain insight into mathematical problems through graphical representation and use modeling as the basis for discovery of basic principles common to all science disciplines. The software allows students to investigate real world problems previously inaccessible using only paper, pencil, and calculator.