MathXpert: Learning mathematics in the 21st century. MathXpert is a computer program designed to help students learn algebra, trigonometry, and one-variable calculus. Its scope extends from elementary algebraic manipulations to the most complicated limits and integrals usually considered in University classes. It is capable of generating complete, step-by-step solutions to mathematical problems, but normally this capability is used to assist the student in developing his or her own step-by-step solution. The design of MathXpert follows principles dictated by its intended use to support learning; these principles and how they influenced MathXpert are discussed. The paper concludes with a discussion of the current and future use of technology in general, and MathXpert in particular, in mathematics education.