This essay describes the results of an experimental class co-taught by an historian and a social studies educator. The class was designed to accomplish two things: to narrow the gap in disciplinary thinking between preservice teachers and historians, and to overcome the preservice teachers' compartmentalized thinking about the nature of their newly acquired historical knowledge and the teaching of it. Through an analysis of the teacher candidates' final projects, which included an historiographic essay, rationale statement, and teaching unit, I demonstrate that the course was only marginally successful with the first objective, but considerably more successful in achieving the second. I suggest that disciplinary thinking may be more useful as a means of improving pedagogy than as an end in itself, and I conclude with a reflection on how the course could have been strengthened. (Contains 1 figure and 7 notes.)