College readiness, particularly with regard to academic writing, has become central to education policy. While this transition seems a natural point where college professors and secondary teachers might build the mutual understandings that “readiness” suggests, little contact occurs. This tendency is unfortunate, because both groups contribute expertise and insight about students’ writing needs. In order to build local, grounded knowledge about college writers and transitions, we invited a group of local secondary English teachers and college writing instructors to a series of School-University Dialogues. This paper reports on the successes and challenges of this three-year, affinity-space-based collaboration, examining its emergent design features over time, as well as evidence of its ability to effect change in teachers’ practices and roles.