As part of the largest, longest running prospective American study of same-sex parent families, the present investigation examined relationship dissolution in planned lesbian families. Data were collected from 40 separated couples and their 17-year-old adolescent offspring--19 girls and 21 boys. Nearly all breakups occurred before the former couples could have obtained the legal equivalent of same-sex marriage in their state of residence. A majority of the mothers rated the communication with their ex-partners as cordial. Seventy-one percent of separated mothers were sharing custody, and they were more likely to do so if the comother had legally adopted the index offspring. There were no differences in adolescent psychological well-being associated with coparent adoption or shared custody. The percentage of adolescents who reported closeness to both mothers was significantly higher in families with coparent adoption.