To help establish common language, to shape a common vision for a science program, guide individual and group reflection on instruction, and support partner teachers in eliciting the involvement of their colleagues, the North Cascades and Olympic Science Partnership created the Science Classroom Observation Guide in 2008. This guide is a tool to organize research-based descriptions of effective science instruction. Here the authors share the guide and some of the many ways people have found to use it in improving their practice.