Though the number of interdisciplinary undergraduate programs has increased rapidly over the past several decades, little empirical research has characterized such programs. In this article we report on our investigation of the characteristics of interdisciplinary programs and develop typologies to describe the multiple ways in which such programs are structured with respect to curricular and organizational features. Using cluster analysis, we show differences in both curricular structures and organizational features across programs, irrespective of the program's content focus. This typology will guide future research to explore differences in student learning outcomes across the interdisciplinary program types.