Interest in interdisciplinary, integrated curriculum development continues to increase. However, teachers who have been given primary responsibility for developing these materials are often working with little guidance. A model for developing theme-based, interdisciplinary, integrated curriculum is presented in this article. The model includes two phases, a theme creation phase and an activity refinement phase. Validity criteria from the interdisciplinary curriculum literature are used to assess the power of potential themes. An integration continuum model is used to facilitate refinement of activities included in the theme-based instruction. The curriculum development model is used to clarify the meaning of the terms theme-based, interdisciplinary, and integrated. The model is intended to be used by curriculum developers to facilitate the creation of powerful interdisciplinary lessons.