The purpose of the study was to determine the effectiveness of a "packaged" language development program, on the general cognitive, intellectual, and language development of preschool children. A selected basic language program (Buchanan Language Readiness Program) and supplementary materials (other language programs), were used to collect data on 13 Head Start classes in Mississippi and Alabama. Different levels of teacher preparation and/or variations in the use of supplementary materials and reinforcement procedures were part of the research design. Four trained classroom monitors, using an intervention checklist designed for the study, reported observations each week for the five experimental groups and twice monthly for the two control groups. (A lengthy anecdotal record is included in this report.) Children were pre- and posttested on selected measures of language development. The standardized tests did not yield significant achievement results, but because of a late start, the prescribed language program was not completed. It is recommended that the following areas receive emphasis: teacher inservice training and supervision, adequate preparation of aides before they are placed in the classroom, parent involvement, and longitudinal studies of children in curricular intervention studies. (NH)