This study examines the learning of a diverse team of five professional developers as they led or supported a mathematics initiative. Although teachers are typically the focus of learning in professional development, we contend that the learning of professional developers is important and should not be overlooked. We examined our learning as a professional development team through first-person inquiry which drew on reflections, conversational accounts and other artefacts. These data sources were used to create a first-person narrative which was analysed for learning according to four domains of change in a model of teacher professional growth. Our findings revealed that this project was rich in opportunities for learning including: learning about mathematics pedagogy; learning about the potential for miscommunication of a message; learning about the challenges of teachers working across multiple agendas and systems trying to support these teachers; and learning about the advantages of team work. Many of these learnings were fortuitous rather than planned. Hence, we now appreciate the importance of being more conscious of the potential for learning in the conduct of professional development projects and to plan for this learning. The paper concludes with challenges for all who undertake or access professional development services in mathematics education. (Contains 4 tables and 2 figures.)