The implementation of the C3 Framework has unfolded unlike any previous standards project. A grassroots movement rather than a top-down mandate, the C3 effort calls on teachers to be at the forefront of social studies reform. In New York State, the C3 Framework provided context and inspiration for the New York Social Studies Toolkit Project. Following the mantra "By Teachers, For Teachers", the Toolkit project empowers classroom teachers as leaders in the development and implementation of innovative curriculum materials animated by the C3 Inquiry Arc. Along the way, "By Teachers, For Teachers" has come to summarize the ethos of a larger movement called C3 Teachers. This article describes the professional learning materials created in the New York State Toolkit Project and how the Toolkit provides a footprint for more sustained and collaborative efforts among C3 Teachers.