Fostering interdisciplinary learning in biology will require significant changes in the way one teaches science to K-12 students. The perspective on interdisciplinary biology teaching and learning in this essay is based on the author's experiences as a former research cell biologist, high school science teacher, and developer of secondary science curricula and teacher professional development programs used in a variety of school districts nationwide. On the basis of these experiences, the author is enthusiastic about the importance of preparing students for the interdisciplinary nature of modern biology, yet concerned about the challenges faced by teachers and school districts as they move toward a modern curriculum. Transforming interdisciplinary biology teaching at the secondary level must include changes in curriculum, instruction, assessments, and teacher professional development in order to support teaching for conceptual understanding and for making cross-disciplinary connections. To prepare students for the nature of modern biology, biology educators must provide them with frequent opportunities to engage in studying interdisciplinary scientific questions or problems. Students will need sufficient time and support to explore, analyze, and reflect on the contributions of various disciplines to advances in modern biology.