A rubric that embodies the key features of the process-oriented, guided-inquiry learning (POGIL) model was subjected to systematic study of validity and reliability. Nearly 60 college instructors used the rubric to evaluate four intentionally modified versions of an established POGIL activity. The modifications strengthened or weakened key characteristics of the activity. Results indicate that the rubric was sufficiently sensitive and reliable for distinguishing the structures of the four versions, even in the hands of those inexperienced with POGIL or the rubric, and that the evaluation was consistent with the design characteristics. The rubric should continue to be useful for reviewing existing classroom materials, for efficient authoring and revising of new materials, and for introducing others to POGIL pedagogy. This article also exemplifies a rigorous process by which a rubric may be evaluated. (Contains 2 tables, 2 boxes, and 1 figure.)