varies across programs, and the programs also vary on the sequencing in which the developmental domains are addressed across treatment years. The developmental areas addressed are discussed below.

Communication It is not possible to directly compare verbal abilities of the children across programs because of differing ages and other potential differences in child populations, but reported data suggest that for many of the model programs, the predictions that only 50 percent of children with autism will develop functional speech (Lord and Paul, 1997) are far exceeded. For example, the Denver Model reported that 73 percent of their preschool graduates were verbal at exit (Rogers and DiLalla, 1991), and Walden reported that 82 percent of children who began intervention as toddlers were functionally verbal by the time they entered preschool (McGee et al., 1999).

Most of the programs reported teaching speech as well as alternative means of communication. Children in several programs (i.e., Denver, Douglass, and TEACCH) were taught speech, sign language, and use of the Picture Exchange Communication Systems (PECS; Bondy and Frost, 1994). All the programs that teach alternative forms of communication maintain a vigorous effort (either simultaneous or sequential) at teaching language development as well. Only Walden formally avows a verbal-only approach to language instruction (McGee et al., 1994, 1999). The Developmental Intervention Model stands alone in focusing on nonverbal communication and interactions rather than teaching verbal language (Greenspan and Wieder, 1997). The Individualized Support Program (and most of the behavioral programs) places a heavy emphasis on development of communication skills that are functional equivalents of problem behaviors (Dunlap and Fox, 1996).

As a rule, the programs that emphasize a naturalistic approach to language intervention focus on conversational language. Thus, both the Douglass (Taylor and Harris, 1995) and the Pivotal Response Model (Koegel et al., 1999a) programs have reported procedures for teaching how to ask questions (e.g., “What’s that?” “Where is it?” “Whose is it?” “What’s happening?”). LEAP and Walden also emphasize the importance of directly teaching verbal interactions with typical peers (McGee et al., 1992; Odom and Strain, 1984).

Engagement Although the terminology in which it is discussed and achieved varies, from the outset of intervention, all of the ten programs either explicitly or implicitly teach engagement. Engagement is defined as sustained attention to an activity or person. The traditional behavioral programs emphasize compliance with one-step directions (e.g., “Sit down,” “Stand up”) as a first step of intervention, with a goal of preparing the child to follow teaching instructions (Lovaas et al., 1981). In the

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