The design research methodology as it has currently developed centers on the creation of "existence proofs," an important first step. What is needed then are the next steps of expanding the methodology to address the design problems of practical implementation prior to the steps involved in scaling up these designs. This article contributes to such an expansion through developing a systematic approach to learning from teachers' enactments of educational models. Design research focused on practical implementations by teachers can create knowledge regarding critical change processes, thus helping to create a theory of trajectories of change, or "implementation paths" (Bielaczyc & Collins, 2006a; Collins, Joseph, & Bielaczyc, 2004). Here I propose using the Social Infrastructure Framework (Bielaczyc, 2006) to analyze the design of classroom social structures by developers and teachers in order to better understand their implications for constructing implementation paths. The analytic technique is exemplified through a case study involving a particular team of teachers who worked over the course of several years to adopt a knowledge-building communities approach (Bereiter, 2002; Scardamalia, 2002; Scardamalia & Bereiter, 1991 1994). The results are used to discuss implications for the methodology of design research. (Contains 2 tables, 9 figures, and 4 footnotes.)