This study considered the facilitators and barriers of successful inclusion in Head Start classrooms by examining the perspectives and practices of instructional professionals. A cross-sectional survey design was combined with direct observation in inclusive Head Start classrooms. Survey data were collected from 71 Head Start instructional professionals in three Head Start programs. Observations took place in nine classrooms to examine the practices of 19 instructional professionals using an observation rating scale. Participants identified a lack of professional development as the greatest barrier to successful inclusion. Participants believed that their inclusion needs were greater than the inclusion supports available to them. Inclusive classroom quality varied significantly among different classrooms. Study findings suggested that the instructional professionals appear to be key to successful inclusion in Head Start settings. Additional professional development for Head Start instructional professionals focused on effectively enacting inclusion practices could support high-quality inclusion for children with disabilities. (author abstract)