This work sought to study participants with consistent Pre-conformist ego development levels during multiple adolescent assessments to determine whether and how their ego levels had changed at age 25. Those individuals whose ego levels remained at the Pre-conformist level were assigned to a life-course-persistent profound ego development arrest trajectory group; those whose ego levels reached the Conformist or Post-conformist level at age 25 were assigned to an adolescence-limited profound ego development arrest trajectory group. Data were derived from a longitudinal project that began in 1978, the full sample of which was deliberately constructed with the goal of capturing a broad range of psychosocial functioning. One group consisted of 76 adolescents drawn from a pool of 250 volunteers from the freshman class of a public high school. The second cohort consisted of 70 adolescents with impairments of sufficient severity to warrant admission to a private specialized child and adolescent psychiatric facility. The group was invited to participate once again as they reached age 25, early adulthood. Tables, references