We examined the evolution of social pretend play in toddlers and tested whether children's age, gender, and language abilities were associated with changes in social pretend play over time. We employed a unique observational data set that followed 28 children (M[subscript age] = 27 months old; 57% boys) with each of two unfamiliar peers over 18 playdates per dyad. Cross-classified multilevel models revealed a quadratic change in the number of successful initiations in toddlers' social pretend play over time with a more pronounced curve for older toddlers. Boys' failed initiations increased linearly over time, whereas girls' failed initiations remained stable. The length of social pretend play did not change significantly over time. Children's age and language abilities were positively associated with successful initiations, failed initiations, and length of social pretend play. Very young children engage in social pretend play and the nature of this play evolves as they get to know one another and form relationships.