His stage theory consists of 8 stages in life from birth to old age, each of which is .
PDF | On Jan 1, , Lisa M. Baumgartner and others published Four Adult Development Theories and Their Implications for Practice.
Eileen M. Brennan and Ann Weick. Theories of Adult Development: Creating a Context for Practice. The assumptions of life-cycle theorists can serve as a basis.
Over the past 20 years, Stevens-Long (, ; Stevens-Long & Commons, ) has been reviewing the state of theory building in the field of adult.