This study examined the effects of staff development and support on Head Start teachers' use of instructional and managerial strategies. Specific research questions were (a) What variables were selected by teachers? and (b) What changes were indicated by the method of support? Observations were conducted for teachers randomly assigned to intervention (n = 14) and control groups (n = 17). Change in instructional variables was determined using a sequential (A-B-C) single case accountability design. Observational data was collected across baseline, a staff development workshop, and support conditions for teachers in the intervention group. Control group classrooms also were measured repeatedly. Results suggest that professional development accompanied by data-based individualized teacher feedback and support can improve teacher use of effective instructional strategies but outcomes were variable. Strengths, challenges, and implications for future research for instructional support models are discussed. (Contains 3 tables and 2 figures.)