Structured interviews were conducted with 19 former career criminals who were at least 35 years old and with 30 middle-aged career criminals in prison. The interview instrument focused on social background, criminal history, life satisfaction, social psychological development, and social desirability (the desire to be socially acceptable). Both former and current middle-aged career criminals largely resembled general-population males in their midlife concerns. These concerns reflect the developmental process outlined in Daniel Levinson's (1978) conceptualization (called 'individuation') of the midlife transitional period. This includes a reappraisal of the past and, based on this reappraisal, planning for the future. The transitional focus is on age, power, gender role, and the concept of self in society. The midlife transition requires a man to find a new balance between opposing forces in each of these four life areas. A comparative analysis of the former and current middle-aged career criminals indicates that midlife desistance from crime largely depends on the existence of well-developed social relationships, work skills, and the resolution of drug and alcohol problems. Supplemental methodological materials and information are appended. Tabular data and 66 references.