Abstract Background The achievement of age-specific developmental milestones in youth is of great importance to the adjustment in adult life. Young adults who were born preterm, might go through a different developmental trajectory and transition into adulthood than their peers. This study aimed to compare the psychosocial developmental trajectory of young adults who were born preterm with peers from the general population. Young adults from the POPS (Project On Preterm and Small for gestational age infants) cohort study, born in 1983 in the Netherlands, completed online the Course of Life Questionnaire (CoLQ - achievement of psychosocial developmental milestones) at 28 years of age. Analysis of variance by group, age and gender was performed to test differences on the CoLQ scale scores between the POPS-group and 211 peers (25–30 years) from the general population (Ref-group). Differences on item level, representing the achievement of individual milestones, were analyzed with logistic regression analyses by group, age and gender. Results The POPS-group (n = 300, 32,3% biased response) scored significantly lower than the Ref-group on the scales Psychosexual Development (effect size − 0.26, p < 0.01), Antisocial Behavior (ES − 0.44, p < 0.001) and Substance Use & Gambling (ES − 0.35, p < .001). A further exploration on item-level revealed, among others, that the POPS-group had their first boyfriend/girlfriend at later age, were more often single, misbehaved less at school and smoked, drank and gambled less than the Ref-group. On the scales Autonomy Development and Social Development no differences were found between the POPS-group and the Ref-group. Conclusions A relatively less vulnerable respondent group of young adults born preterm showed some psychosocial developmental trajectory delays and might benefit from support at teenage age. Because of the non-response bias, we hypothesize that the total group of young adults born preterm will show more severe psychosocial developmental problems.