The purpose of this article is to describe the adaptation process of an evidence-based early childhood Tier-2 intervention program, BEST in CLASS-Prekindergarten, from a face-to-face format to a web-based delivery format called BEST in CLASS-Web. We describe the three-phase iterative development process used to adapt the parent program for delivery via the web. Activities in these phases included focus groups, interviews, an expert panel review, alpha and beta testing (Phase 1), feasibility testing (Phase 2), and a pilot promise study (Phase 3). Each phase included a series of refinements and improvements to materials based on data and stakeholder feedback. Lessons learned and implications for developing and implementing professional development services via online platforms are discussed. [This article was published in "Journal of Educational Technology Systems" (EJ1304247).]