Structural-interactive vocational theory shows that both aspirational and work histories have continuity over the life span and provide useful explanations of stability and change. This paper suggests some implications of structural-interactive theory for the study of adult development. Common principles of structural-interactive theories are outlined, and the importance of career data in daily life and research is discussed. The relationship of career continuity to personality is explored, and stability and change are discussed in terms of interactive career theories. Research is reviewed to support assumptions of interactive career theory as well as personality and learning theory. Implications of vocational theory for the study of adult development and for providing mental health and vocational services to both younger and older adults are highlighted. (JAC)