Increasing numbers of gender nonconforming children are socially-transitioning-changing pronouns to live as their identified genders. We studied a cohort of gender nonconforming children (N=85). When re-contacted approximately 2 years later, 36 of the children had socially-transitioned. We found that stronger cross-sex identification and preferences expressed by gender nonconforming children at initial testing predicted whether they later socially-transitioned. We then compared the gender nonconforming children to groups of transitioned transgender children (N=84) and gender conforming controls (N=85). Children from our longitudinal cohort who would later transition were highly similar to transgender children and control children of the gender to which they would eventually transition, while gender nonconforming children who would not go on to transition were different from these groups. These results suggest that (a) social transitions may be predictable from gender identification and preferences and (b) gender identification and preferences may not meaningfully differ before and after social transitions.