Wenger's theory of learning proposes the concepts of "participation" and "reification" as dimensions of educational design. Based on this proposal, this position paper looks at the design of one Mathematics Professional Development Program (MPDP) through the lenses of these concepts. We argue that the "reification" concept allows professional designers to keep in mind the resources they should use to organize teachers' learning, while the "participation" concept allows them to ponder the types of activities that should be implemented in order for the teachers to adequately assimilate the meaning of those resources. The example that serves as the context in which we situate our discussion is the Data Analysis Project, a professional development project on statistics in which 5 in-service secondary school teachers participated. Due to the dialectic relation between "participation" and "reification," we explain how these two processes intertwine to maintain the balance needed to allow teachers' learning to proceed within an MPDP. We argue that this dialectic relation is the key element for MPDP designers to connect the resources produced by research in mathematics education to the practice of mathematics teaching. Such a connection allows an MPDP to act as a bridge between two communities of practice: that of researchers in the field of mathematics education and that of mathematics teachers. Ultimately, the article shows how Wegner's concepts of "participation" and "reification" may be used to design an MPDP.