Inconsistent findings exist on the effects of young adult-parent relationships on developmental status transitions into adulthood. Such transitions in turn predicted less conflicted and closer young adult-parent relationships. But systematic investigations of reciprocal effects between developmental transitions and young adult-parent relationships are lacking. A total of 477 participants initially aged 20-32 (M = 23.9, SD = 1.5) were interviewed twice, once in 1993 and again in 1995/1996. Subsamples were drawn that had not yet undergone the transitions to work, leaving home, cohabitation with a romantic partner, marriage and parenthood at Time 1. It was assessed whether the levels of mutual trust, instrumentality of relationships, and critical discussions at Time 1 predicted developmental transitions by Time 2, and whether developmental transitions were followed by changes in the relationship measures. The more the participants trusted in their parents, the more likely they were to marry or to have children. Cohabitation was followed by decreased instrumentality. Higher discussion frequency predicted cohabitation and was a consequence of starting to work and leaving home. The results are discussed with regard to individuation theory of adolescent and young adult-parent relationship development.