The two presented studies examine outcomes of in vitro fertilization (IVF)-conceived twins relative to IVF singletons and their families in adolescence (Study 1: n = 194 families, Study 2: n = 192 families). Study 1 used nested ANCOVAs to examine differences in family environment and adolescent adjustment outcomes among 11 -- 17 year-old IVF twins and IVF singletons and their families. Despite notable statistical power, there were no differences between adolescent-aged IVF twins and IVF singletons and their families. This suggests IVF twins and their families function well into adolescence. Study 2 tested two autoregressive path models that propose parental conformity expectations have differential effects on twins' and singletons' parent-adolescent relationship satisfaction, which indirectly accounts for relative changes in twins' and singletons' adjustment over time. Despite the developmental need for increased autonomy in adolescence, results indicate high conformity expectations play a positive role for adolescent-aged twins and their families. These studies suggest that, while adolescent IVF twins and IVF singletons and their families function well, research on singletons should not be universally applied to understand twins and their families.