Data were obtained in a cross-sectional survey conducted in five youth custody institutions in Northern Germany in the spring and summer of 1998. The participants were 299 male German prisoners between the ages of 14 and 24 who were serving a custodial sentence for the first time. First-time prisoners were selected because the researchers anticipated that their experiences of imprisonment would be especially painful for them. Standardized oral interviews were conducted in the prisons between April and August 1998 by trained interviewers. Self-esteem was assessed with the Self-Esteem Scale. Individual inclination to react accommodatively to onerous experiences or circumstances was assessed with the Flexibility of Goal Adjustment questionnaire. The study found that the stability of self-esteem during incarceration depended on both accommodative and immunizing coping reactions. Prisoners who did not have at least one of these coping resources manifested particularly low self-esteem at the start of their term of imprisonment. This creates the misleading impression that for the average individual, self-esteem increases during a period of custody. This study also shows that in the latter period of a prison term, accommodative coping resources also tended to support an increase in immunizing reactions. Implications for longitudinal studies and for practical interventions in the juvenile custody system are discussed. 5 figures and 86 references