In the present work, we ask whether socially transitioned, transgender children differ from other children in their endorsement of gender stereotypes and response to others' gender nonconformity. We compare transgender children (N = 56) to a group of siblings of transgender children (N = 37), and a group of unrelated control participants (N = 56) during middle childhood (ages 6-8 years old). Our results indicate that transgender children and the siblings of transgender children endorse gender stereotypes less than the control group. Further, transgender children see violations of gender stereotypes as more acceptable, and they are more willing to indicate a desire to befriend and attend school with someone who violates gender stereotypes than the control participants. These results held after statistically controlling for demographic differences between families with and without transgender children. We discuss several possible reasons that can explain these differences.