In order to understand learning in adulthood, we need to understand developmental changes across the latter half of the lifespan. The purpose of this chapter is to discuss a number of contemporary adult developmental theories that explain changes in different domains of functioning. For instance, strategies for dealing with a novel situation may be different for young and older adults as a function of changes in processing goals. When faced with a new situation, young adults may focus on developing and optimizing new strategies to adapt to the problem situation. Older adults, however, may draw upon an accumulated wealth of strategies in order to regain or maintain a viable solution. Adult development theories can provide us with explanations as to why and how individuals change such processing goals that impact the way they approach the problem.