Consultation is a promising approach to creating change in early childhood programs, from innovations in instructional strategies to the enhancement of global program quality. Studies of consultation effectiveness have been hampered by limited reports of implementation fidelity related to consultation procedures. This article describes the challenges of supporting and measuring implementation fidelity in a 5-state study in which community consultants followed a collaborative consultation model to enhance global quality in childcare programs. The authors consider the limitations of using a randomized experimental design to study the effectiveness of consultation and share lessons learned in their efforts to enhance treatment fidelity without compromising the basic tenets of the model or the rigorous design. (Contains 1 table.)