Research Findings: This article is a natural follow-up to intent-to-treat findings indicating that the MyTeachingPartner Consultancy, inclusive of online video resources and Web-mediated consultation, improved the quality of pre-K teachers' interactions with children. This study takes a close look at implementation fidelity within the effective MTP Consultancy condition over both years of implementation, in order to learn more about the ingredients of professional development that may have contributed to the success of the intervention. Practice or Policy: Variation in teachers' responsiveness (e.g., ratings of Consultancy worth) and exposure to the intervention (e.g., number of consultation cycles completed) are examined, with particular interest in the identification of teacher factors that may serve as supports or barriers to successfully implementing consultation supports and online professional development resources. (Contains 5 tables.)