Abstract: | A stochastic actor‐based model was used to investigate the origins of sex segregation by examining how similarity in sex of peers and time spent in gender‐typed activities affected affiliation network selection and how peers influenced children's (N = 292; Mage = 4.3 years) activity involvement. Gender had powerful effects on interactions through direct and indirect pathways. Children selected playmates of the same sex and with similar levels of gender‐typed activities. Selection based on gender‐typed activities partially mediated selection based on sex of peers. Children influenced one another's engagement in gender‐typed activities. When mechanisms producing sex segregation were compared, the largest contributor was selection based on sex of peers; less was due to activity‐based selection and peer influence. Implications for sex segregation and gender development are discussed. |