This qualitative, multicase study examined the perceived effect on teachers of an online professional development (PD) program supported by facilitators who provided extensive feedback to them. Our goal was to identify the barriers to teachers implementing their learning in their diverse contexts. Using inductive and deductive thematic analysis and cross-case analysis of interviews and reflections, we found that positive results are much more likely if the design of PD is contextual and facilitation is in place. However, for this external PD to be effective, barriers to implementation, such as administration or support, school policies, and context need to be considered. The nature of PD does not guarantee the implementation of what was learned in the classroom. Suggestions for improvements in terms of PD design and barriers are also discussed.