The purpose of this paper is to describe effective methods of developing pretend play that is intrinsically motivating for young children with autism spectrum disorder (ASD) using the topic of circumscribed interests. Children with ASD often develop very specialized interests, known as Circumscribed Interests (CI). However, their limited and intense interests are often perceived by others, especially by parents, as interfering with their learning and social interactions with others. This paper reports how one parent fostered pretend play in her preschool child with autism based on his CI in "trains." Four steps for promoting pretend play for preschool children with autism using their topic of interest are presented. These include (1) Creating a web, (2) Modeling pretend play through use of divergent materials, (3) Modeling verbal interaction in pretend play, and (4) Providing theme boxes and field trips/excursions. The author concludes that the four steps are useful for not only fostering their active involvement in pretend play, but also in helping their topic of special interest expand into a wide range of pretend play. In addition, creating webs based on CI may enable caregivers or teachers to intentionally provide meaningful experience with specific outcomes in mind for children with autism.