Children with typical development utilize social-cognitive skills (e.g., joint attention, imitation) and word learning constraints to quickly learn new words (i.e., fast-map). However, few studies have investigated fast-mapping in children with autism spectrum disorders (ASD) and the effects that social-cognitive skills have on word learning. The objectives of the current study were to examine the following questions: (1) Do preschoolers with ASD and preschoolers with typical development fast-map at similar rates?; (2) Do preschoolers with ASD utilize word learning constraints?; and (3) What is the relationship between joint attention, imitation, and fast-mapping in preschoolers with ASD? Preschoolers with ASD and typical development completed a basic fast-mapping condition (i.e., the ability to link a novel label with a novel object) and 3 conditions measuring the uses of word learning constraints; (1) Mutual Exclusivity - examined the ability to assume that a novel label applies to a novel object; (2) Taxonomic - examined the ability to assume that novel labels extend to objects that are similar in shape; and (3) Whole-Object - examined the ability to assume that novel labels refer to whole objects. Various assessments measured language, joint attention, and imitation skills. Results revealed that children with ASD showed equivalent word learning to children with typical development in the basic fast-mapping condition. This intact word learning occurred despite significantly lower joint attention and imitation skills. However, children with ASD were less effective at using word learning constraints, showing significantly less word learning in these conditions than children with typical development. Further, while increased joint attention was related to performance in the mutual exclusivity and taxonomic constraints for both diagnostic groups, joint attention was only related to performance in the basic fast-mapping condition for children with typical development. Overall, preschoolers with ASD fast-mapped and learned new words in a similar manner to children with typical development, despite impairments in joint attention and imitation. However, children with ASD were less accurate at utilizing word learning constraints. Although research has emphasized the link between social-cognitive skills and language, the current study suggests that children with ASD may be utilizing alternative strategies or skills to increase their vocabulary.