Study data were collected in three ways: personal interviews with 50 men previously incarcerated for ordinary property crime, and released from Federal penal institutions between 1955 and 1968, examination of arrest and correctional records for each of the 50, and systematic examination of autobiographies of comparable offenders. When interviewed in 1980-81, very few of the men were still engaged in crime. They had experienced two types of changes in their lives, orientational and interpersonal, which led them to modify their calculus of ordinary property crime. In turn, this led to changes in the frequency and visibility of their criminal behavior. The findings thus confirm that advancing age produces decreasing rates of involvement in major property crimes. However, the exact mechanism for the maturation effect, or the decrease in crime with increase in age, has remained unclear. Some of the age-related changes the subjects experienced differ little from those experienced by nonoffenders. Consequently, the findings challenge certain critical assumptions about offenders used as arguments by contemporary advocates of repressive crime control measures. The subjects tended to modify their aspirations with honest appraisals of the possibilities. They began to consider the transitory aspects of life itself and thus determined to use the remaining time more wisely. Although most of the changes ex-offenders experienced parallel those of nonoffenders, ex-offenders also reported weariness with the lifestyle of the ordinary property offender. It is concluded that crime control efforts should attempt to stimulate the natural psychological changes that occur during the aging process in both ex-offenders and nonoffenders. A bibliography and a copy of the interview guide follow the text.