Background: A significant body of scholarship has highlighted the importance of improvisation in teaching, particularly the interactional and responsive creativity that is required for teachers to co-construct meaning with students. However, recent efforts inside and outside university-based teacher education have pushed against novice teacher learning through improvisation, preferring to focus on the "practicing" of identifiable components or discrete techniques of teaching. Purpose: Based on an expansive view of practice, I argue that improvisation is inextricably connected to practice and illustrate that the marginalization of improvisation limits opportunities for novice teachers to learn the relational aspects of teaching. I develop the concept of principled improvisation: improvisation that is purposefully oriented toward justice and that accentuates each moment of teaching as political, ethical, and consequential. I describe the design of a learning environment for preservice teachers that was organized around principled improvisation and demonstrate its unique affordances for particular forms of novice teacher learning. Research Design: Based on a close reading of novice teachers' weekly reflections and audio recordings and field notes from the whole-class discussions, I highlight five examples of practice guided by principled improvisation that span a diversity of participants, contexts, and scale. These illustrative cases are not meant to systematically characterize all instances of practice guided by principled improvisation in the course; rather, they are meant to be invitations to grapple with new pedagogical and learning possibilities (and limitations) that emerge when teacher education is organized around principled improvisation. In particular, I explore how learning to listen played prominently in teacher practice guided by principled improvisation and examine how the opportunity to narrate, re-narrate, and re-envision experiences allowed novice teachers to learn and collectively build place-relevant theory. Conclusions: The opportunities to learn to recognize emotion, listen, see race in place, consider political expression, and make sense of power across scales were significant aspects of the relational work of teachers that were learned by organizing novice teacher learning around principled improvisation. These forms of learning could not have taken place if the experiences of the novice teacher were only organized around the rehearsal of components of teaching. It required teaching in a complex space that connects self and interactions in place to larger structures and ideologies in society.