This article is the second in a series (see Willis, 2011) that looks at the current status of instructional design scholarship and theory. In this concluding article, the focus is on two cultures of ID work, one based on constructivist and interpretivist theory and the other based on critical theory and critical pedagogy. There are distinct advantages and disadvantages to ID models based on these two foundations, and the same is true of models based on traditional behavioral theory and contemporary cognitive science/learning sciences. A desirable approach to making decisions about what foundation to base ID practice on may be to borrow ideas, concepts, and practices across different theoretical and conceptual foundations rather than adopting a fundamentalist perspective. (Contains 2 figures.) [For Part One, see EJ917283.]