To monitor and evaluate program success and to provide teachers with a tool that could support their transformation in teaching practice, we needed an effective and valid protocol to measure the quantity and quality of inquiry-based instruction being led. Existing protocols, though helpful, were either too generic or too program specific. Consequently, we developed the Electronic Quality of Inquiry Protocol (EQUIP). This manuscript examines the 2-year development cycle for the creation and validation of EQUIP. The protocol evolved over several iterations and was supported by validity checks and confirmatory factor analysis. The protocol's strength is further supported by high internal consistency and solid interrater agreement. The resulting protocol assesses 19 indicators aligned with four constructs: instruction, curriculum, assessment, and discourse. For teachers, EQUIP provides a framework to make their instructional practice more intentional as they strive to increase the quantity and quality of inquiry instruction. For researchers, EQUIP provides an instrument to analyze the quantity and quality of inquiry being implemented, which can be beneficial in evaluating professional development projects.