Proponents of a blended course paint an ideal picture of participants leisurely learning and reflecting on how they can apply their new knowledge. The reality is of course much more complex, especially in the lives of working adults. This study sought to understand the complexity better through analysing the experience of 123 participants enrolled in the 9-h in-service blended course. In particular, it investigated participants' engagement by examining their experience as they interacted with elements of the blended environment. The mixed methods approach was employed with quantitative data from the course analytics and responses from the 34 participants who returned the evaluation questionnaire at the end of the course. This was complemented with one-to-one interviews with 10 participants. The findings suggest that designers of blended professional development courses should bear in mind the characteristics of both the learner and the online platform to achieve greater cognitive, behavioural and social engagement.