This article begins with a history of play therapy in the United States and then focuses on psychodynamic play therapy using pretend play with young children. Pretend play is initiated by parents in the crib, using marked affect. In almost all cultures, child-initiated Imaginary play emerges on the same timetable (18-24 months) and then blossoms in the young toddler who engages in solitary play for 2 or more years. With the maturation of ego capacities, such as mentalization, play transforms into the social play of the pre-Kindergarten/Kindergarten years, where children collaborate in making believe.