Teacher education for sustainability (TEfS) aims to prepare future educators for their role as societal change agents by developing in them specific sustainability competencies. Whereas previous literature has dealt extensively with concepts and empirical work connected to learning objectives in TEfS, this paper links these learning outcomes, or what student teachers learn in individual course offerings, to the learning process—how they learn. In this way, we reveal factors of common teaching and learning formats in TEfS that may either foster learning or hinder it. At Arizona State University (ASU), the TEfS course Sustainability Science for Teachers (SSfT) is a mandatory component of all elementary-education (K–8) programs. As similar requirements appear in more and more teacher-education programs, it is important to understand how learning in course offerings like SSfT should be designed in order to best support student achievement of intended learning outcomes. More than 100 pre-service teachers and four instructors, all taking or teaching the SSfT course at ASU, participated in this single explanatory case study, which adopted a mixed-methods approach. To richly portray students’ learning processes, as well as the outcomes of their learning in the course, this study involved non-participatory observations, a pre/post-course survey, end-of-semester focus groups, and semi-structured interviews. Its findings suggest that four forms of connection (the 4 Cs) namely personal, professional, social, and structural, are particularly impactful on students’ learning in the SSfT course. Finally, these insights are accompanied by a set of recommendations as to what to consider when planning and designing similar TEfS course offerings. Future research should focus on the K–12 students of educators trained in education for sustainability (EfS) to understand the extent to which educators can use their new skills and knowledge to empower and motivate K–12 students to persistently engage in real-world projects that contribute to systemic change.