In this paper we discuss our development and use of a conjecture map for a large research project on the design and implementation of an online professional development model. Following Sandoval's (2014) model, we built the conjecture map to reflect our high-level conjectures (overarching goals of the project), the embodiment of the learning design, the mediating processes, and the outcomes. After roughly half a dozen iterations to ensure that we accurately and fully captured the features of the learning environment and the mediating processes, we used the conjecture map as an anchor for a number of our data analysis activities, particularly of our online course modules, and for initiating theory-building processes. We also found that it was an expedient way to communicate internally and externally the core assumptions and learning principles of our multifaceted online professional development model. [For the complete proceedings, see ED606531.]