There is growing recognition of the importance of engaging postsecondary students in experiences that challenge them to solve complex socioscientific problems, transdisciplinary in nature, requiring students to integrate and synthesize knowledge, skills, and ways of thinking across disciplinary boundaries. Yet these student experiences are atypical. One possible reason is that the cross-disciplinary collaborations of faculty needed to create meaningful transdisciplinary student experiences are likely to be challenging. Lacking insight into these novel collaborations, we conducted a phenomenological study that describes faculty experiences across multiple disciplines and institutions to develop a transdisciplinary curriculum. Faculty were motivated by their professional development needs and a desire to improve their teaching practices and to develop curricula that would enhance student learning, all around a topic of personal interest. Yet faculty experienced tensions related to navigating norms, practices, and language across disciplines, the suitability of transdisciplinary curricula to their courses, and confidence in teaching across disciplines. Project leaders were essential facilitators and codevelopers, helping to alleviate some tensions. We discuss implications for faculty, academic leaders, administrators, and other stakeholders interested in involving faculty working across disciplines to develop transdisciplinary curricula, notably around a timely and important topic in the biological sciences.