Children in traditional families (i.e., married, 2 biological parents) tend to do better than their peers in nontraditional families. An exception to this pattern appears to be children from same-sex parent families. Children with lesbian mothers or gay fathers do not exhibit the poorer outcomes typically associated with nontraditional families. Studies of same-sex parent families, however, have relied on a static conceptualization of the family and discounted the importance of the timing and number of family transitions for understanding children's outcomes. To examine whether same-sex parent families represent an exception among nontraditional families, the author used data from the Early Childhood Longitudinal Study--Kindergarten cohort (N = 19,043) to create a dynamic indicator of children's family structure and tested its association with math assessment scores. The results indicated that children in same-sex parent families scored lower than their peers in married, 2-biological parent households, but the difference was nonsignificant net of family transitions.