Gender identity development begins in early childhood and intersects with many facets of growth across the life span. Psychologists have sought to understand this aspect of development for decades, and it continues to be a salient area for researchers and practitioners alike. Although there are numerous theories to explain gender identity development, consensus is lacking regarding which one, or [Page 671]combination, offers the best explanation. The growing research on transgender and gender nonconforming (TGNC) children has added a new element to this conversation. This entry outlines the major theories and typical development of both cisgender and TGNC children, from birth to 11 years of age. Cisgender refers to a gender identity that aligns with an individual’s gender assigned at birth, which is often consistent with ...