Interdisciplinary undergraduate programs have grown dramatically in recent decades, but they are vulnerable to cuts given various stakeholders' calls for greater accountability in higher education. Assessing the outcomes of interdisciplinary majors presents an array of challenges, including how to describe and categorize patterned variation in the place and purpose of disciplines in interdisciplinary programs. Knight, Lattuca, Kimball, and Reason's (2013) typology conceptualizes this variation in terms of curricular features and staffing of interdisciplinary programs, and asserts that stronger programs are marked by less reliance on disciplinary courses and faculty whose lines are in disciplinary departments. We argue that another important source of variation is the approach taken to interdisciplinary education: how the program connects disciplines (e.g., via integration or juxtaposition) and what the program aims to foster (depth, breadth, or specific skills). Attending to these aspects of variation in interdisciplinary programs improves the Knight et al. framework insofar as it permits investigation of which combinations of interdisciplinary approaches, curricular design, and staffing might best foster particular educational aims. We demonstrate the utility of this improved framework by applying it to a recently completed external review of an interdisciplinary program at a liberal arts college (ours). We offer some suggestions for how to align different approaches to interdisciplinary education with an institution's general curriculum, the major's curriculum, and program staffing.