This study will examine the relative effectiveness of two communication interventions on the production of speech in 40 preschool children with ASD (3 to 6 years) who are pre-linguistic i.e. produce fewer than 10 different words. The two experimental treatments will be added to whatever interventions the child is receiving the community. The primary aim is to assess the effectiveness of a direct speech-focused treatment versus a naturalistic approach on the production of speech and the adaptive use of verbal communication. The study will also determine the effect of a parent-delivered generalization program on the maintenance of gains of the interventions provided. The two treatments that will be compared are a direct speech-focused treatment, the Rapid Motor Imitation Training, that reinforces motor imitation (and later targets verbal requests and labels) versus a naturalistic approach the Prelinguistic Milieu Teaching (PMT), which has been demonstrated to be effective in increasing communicative behavior in young children with various developmental disabilities. At the end of the treatment period, the children will be assessed by the number of spoken words and expressive communication level. Further, in an effort to match child traits to the most appropriate treatment approach, the data will be analyzed to determine which child characteristics prior to the intervention are associated with greater gains in either of the two treatments. What this means for people with autism: This project aims to compare the effectiveness of two established behavioral treatments aimed at improving language and communication abilities in preverbal, preschool children with ASD. It will advance evidence-based practice in the early intervention arena. It will also supply useful information for predicting the best treatment method to use with children who have particular profiles of prelinguistic development, so as to provide the most effective match between child and intervention.