Theories about adult development have been grouped into four models: biological, psychological, sociocultural, and integrative. Biological models (those that are concerned with how physical changes affect development) and psychological models (those that view development as either sequential--defined by life events-- or as a series of transitions or as relational) have long been part of the adult education literature. Sociocultural and integrative models represent new ways of thinking about the influence of adult development on adult education. Sociocultural perspectives of adult development have as their primary focus the social and cultural aspects of adult lives. Factors such as race, gender, class, and sexual orientation are considered important aspects of development in these models, including how these factors intersect and affect how adults develop. Integrative models examine how the biological, psychological, and sociocultural aspects of adult development intersect and influence each other, but models that consider all three perspectives are rare. Because of their recognition of the complexity of the factors that influence how adults learn and grow, integrative models seem to hold the most promise for understanding adult development. The role of transformative learning in adult development is another area that has received a great deal of attention recently. (The paper lists and summarizes 22 resources in the field of adult development and education.) (KC)