Abstract: Teachers' adherence to designed curricular expectations is an important area of focus of investigation concerning the fidelity of implementation of curriculum. However, with open-ended curricula such as problem-based learning (PBL), the concept of adherence to curricular expectations is less focused on ensuring that "correct" answers are achieved, but instead on ensuring that the processes of PBL and other open-ended activities and pedagogy are maintained. To this end, teachers often need support with adhering to prescribed curricular activities and pedagogical activities when implementing a novel curriculum. In this paper, the outcomes of a form of online professional development called responsive ongoing professional development (ROPD) are investigated to identify how participation in ROPD predicts curriculum implementation adherence. ROPD participation by 26 middle-school social studies teachers in the United States was analyzed over a semester of implementing a blended-learning curriculum called GlobalEd. While accounting for teachers' number of years of experience with the curriculum, findings show that participation in online, ongoing ROPD strongly predicts high levels of adherence among teachers. Although ROPD is but only one of many factors that likely explain adherence, such participation nonetheless serves as a valuable tool for intervention implementation and as a learning analytics indicator for the health of a curriculum implementation in real-time.