Use of the term "crisis" to define the midlife era suggests a limited sense of choice and control. The term "transition," however, emphasizes a process of change and suggests that the individual has both choice and power to grow and develop. An open-ended questionnaire was sent to professionals (N=42) in medical, psychological, sociological, and direct service areas. Data representing interdisciplinary fields of human and family development, developmental psychology, industrial psychology, adult education, family sociology, and vocational counseling were also collected from 21 respondents. The professionals reflected on chronological, physiological, sociological, and psychological dimensions of the phenomenon of midlife. Several events marking midlife were indicated by respondents. For one variable, midlife career change, professionals rank ordered factors that would be influential on the career changer. Marriage was ranked as the most important system, followed by the immediate family, and the social networks of friends and coworkers. A synthesis of responses defined midlife as the age interval of early 30s to late 50s which represented a process of managing change in discrete situations. The findings suggest that growth, maintenance, or stagnation may result from the strategies used to manage one's lifestyle during midlife change. (NRB)