In this paper, we frame the dissemination of the products of classroom design studies as a process of supporting the learning of large numbers of teachers. We argue that high-quality pull-out professional development is essential but not sufficient, and go on to consider teacher collaboration and one-on-one coaching in the classroom as additional supports. We then illustrate that it is also important to identify other aspects of the school context that need to be addressed by a dissemination design, such as school instructional leadership and teachers' access to colleagues who have already developed relatively accomplished instructional practices. We conclude by discussing how researchers who conduct classroom design studies can make the challenges of dissemination more tractable by designing with an eye towards large-scale implementation. Our suggestions include that they make the design study teacher's relatively sophisticated instructional practices an explicit focus of analysis and that they assess whether it is realistic to expect teachers to learn to enact the products of the study effectively given their current instructional practices and the capacity of educational systems to support their learning.