Studies investigating the effectiveness of professional development (PD) programs have provided no conclusive findings on what exactly makes a PD effort effective. Using an observation-based coaching PD program, we explore which features in the PD implementation process facilitated or impeded teachers' meaningful engagement in and learning from the PD program. We interviewed seven PD coaches and a selection of 11 teachers involved in a 3-year PD project. We found that how the school and the coach implemented the PD project played a critical role in shaping teachers' willingness to participate in the program. We conclude that the success of a PD program depends not only on enduring effective PD features but also and especially on the PD implementation process within the context of daily school life.