Online teacher professional development (oTPD) provision has seen a rapid increase in recent years, with significant growth during the COVID-19 pandemic. However, concerns persist around equitable access, course retention and completion, the relevance of materials for varied contexts, and the level of engagement that is realistically possible. More research is needed regarding the ways in which learners in these contexts engage in learning and the impact on their practice. Using a phenomenological approach (Creswell 2013), this paper identifies and documents educators' perceptions and real, lived experiences of oTPD during a Massive Open Online Course (MOOC) entitled 'The Fundamentals of Educational Dialogue'. Findings indicate that educators' perceptions of oTPD impact and correlate with their experiences. Participants are responsive to how courses are designed (e.g. course aims, structure, cost, and opportunities to meaningfully connect with other practitioners), which influences their engagement in the course and levels of interaction with peers, and ultimately affects the ways in which the course impacts their personal and professional lives. Implications for future oTPD courses include utilising a framework that recognises learners as reflective, critical professionals who shape their own and others' experiences. This encourages a view of capacity building as not ending with the acquisition of subject knowledge alone but rather results in a greater depth of learning, particularly when dialogue is used as a pedagogical tool to co-create new knowledge. This intentional sharing of perspectives and reflective engagement with the differences therein can ultimately contribute to fostering a sustainable community of practice.