Gender is a salient schema in everyday life. Research has become increasingly aware of the influence of gender stereotypes on development. Gender nonconformity has received much attention both inside and outside academia recently. This talk presents three studies on childhood gender nonconformity. Gender-nonconforming (GN) children are often perceived less positively, which may harm their well-being. Study 1 examined the development of such perceptions using multiple measures (verbal responses on friendship preference, perceived popularity, emotion perception, activity preferences and moral judgment; behavioral measures on sharing and ranking). The results showed that children were less positive towards GN than gender-conforming (GC) peers, especially if they were older or if the peers were boys. Study 2 developed an intervention to modify the negative appraisals of GN children. By showing children exemplars of GN peers who displayed positive and GC characteristics, bias against gender nonconformity was reduced. Study 3 examined the reasoning styles children used to evaluate peers of different gender expression. Differences in culture, age, gender of peers, and correctness of peers (i.e., perceiving the peers as right vs. not right) were found in children’s reasoning styles. Overall, the findings enhance our understanding of children’s appraisals and inform strategies aimed at reducing bias against gender nonconformity. Gender nonconformity, which is not uncommon, is increasing in frequency and visibility worldwide. Enhancing tolerance of diversity has been shown to bring positive effects to the society’s wellbeing and prosperity.