This chapter explains the psychological concerns in the teaching and learning of mathematics. It discusses what the National Council of Teachers of Mathematics calls mathematical disposition—the attitudinal side of teaching mathematics—and how it develops over time, including how mathematics anxiety emerges in some students. The chapter describes several current learning theories and their implications in the classroom. It aims to trace the development of general learning psychology and then elaborate on the theories of Jerome Bruner and the van Hieles as well as the constructivist model, which have direct applications in the teaching and learning of mathematics. In classical behavioral psychology, the belief is that learning can be controlled by the application of external rewards and punishments. B. F. Skinner, probably the best known of the behaviorists, described how a dog could be taught to sit by giving it food treats.