Developing instructional capacity in schools is a central challenge of the Common Core movement. Most conceptualizations of capacity building focus on infusing externally generated professional development into schools. In this article, we explore the professional resources that reside inside schools that might be utilized to develop instructional capacity from within. Overall, we found that an abundance of these resources existed in schools, but they were unevenly distributed across and within schools. We also found that coaches and administrators were more likely to be recipients for requests for assistance and that they tended to have more Common Core subject matter knowledge, on average, than teachers did. We also found that external resource seeking was correlated with Common Core knowledge and with those who were recipients of requests for advice from colleagues. The article concludes with a discussion of the implications of these findings for research and practice.