Convicted criminals are often punished with temporary detainment in correctional institutions. However, many do not have a corrective experience and come in and out of custody as though there were a revolving door, further entrenched in criminality upon release. Each time a repeat offender reenters the community he is at an impasse. The choices can be reduced to recidivism or desistance from crime. In other words, he can continue his criminal career, reoffend, and be remanded into custody or he can make a change, abstain from crime, and work towards maintaining a crime-free lifestyle. In order to promote the latter, this process of change must be better understood. The present study investigated the psychological changes that are associated with long-term desistance from criminal behavior. Grounded theory methodology was employed to develop a hypothesis about the psychology behind criminal desistance. The experiences of reformed career offenders were accessed directly using in-depth interviews inquiring about past and present experiences, ideas about transformation, and beliefs about criminal desistance. The participants consisted of 4 men and 1 woman who stopped engaging in illegal behavior for at least 3 years after an extensive criminal past. The findings demonstrated that long-term criminal desistance is accompanied by an increase in prosocial impulses. The strength of the prosocial impulse is the product of other psychological phenomena including thoughts about change, self-reflection, psychological growth, feelings of connectedness to prosocial objects, and ongoing motivation to remain crime-free. Prosocial impulses refer to thoughts and feelings that promote the well-being of the self and humankind. Some basic examples of prosocial impulses include empathy, gratitude, honesty, accountability, hope, helping, curiosity, acceptance, and humor. The suggestion that prosocial impulses are positively related to long-term criminal desistance is unique to this research.