The purpose of this study is to investigate whether or not students' understanding of mathematical content typically covered in calculus courses is enhanced by using the TINspire CAS instead of the TI-89. The study was conducted over two phases at a mid-size university in the northeastern United States in Calculus I and Accelerated Calculus I. In Phase 1, the TI-Nspire CAS calculator was used sporadically throughout one semester in experimental groups, while control groups used only the TI-89 calculator. Statistically significant differences favoring the TI-Nspire CAS group occurred on 2 of 6 quizzes in Calculus I, but no statistically significant differences were found in Accelerated Calculus I. In Phase 2, the TI-Nspire CAS was used during every class of one semester in experimental groups, while control groups used only the TI-89. No statistically significant differences were found in Calculus I, but statistically significant differences favoring the TI-Nspire CAS group occurred on the last 2 of 7 quizzes in Accelerated Calculus I. Students reported a very steep learning curve when using the TI-Nspire CAS, causing up to a whole semester of fully integrated use to become comfortable enough to use it effectively. They appreciated the dynamic graphical capabilities, especially grab-and-drag and data-capture features. However, they were indifferent to "pretty print" symbolic manipulations, holding the belief that they should know how to do calculations by hand. Recommendations for educators are provided.