Designing human-centered interventions that enable sustainable choices by individuals, institutions, industries, and nations is crucial for our future. In this course, Human-Centered Design (HCD) and Behavior Change Science tools come together to shape sustainable and environmental behaviors and understanding. As a project-based learning class, much of the learning is experiential and emergent, applied through a 10-day design sprint challenge and an 8-week real-world team design challenge with an external partner. This semester, our partner is OpenFung, a nonprofit organization creating the tools, knowledge, and networks to position fungi as a viable and sustainable building material. Students will work to bridge the information gap between scientists and the public, utilizing regenerative, mushroom-based materials, and increase the adoption of building with these materials through the use of design tools. The course is rich in both theory and practice, as students are introduced to a diverse range of mindsets, skill sets, and design applications. Students gain applied behavior change research skills, equity-focused human-centered design skills, and professional teamwork and client communication skills.