In this commentary, I present a model based on sociocultural theory showing how intrapersonal, cognitive, and interpersonal competencies are jointly developed through discipline-specific, ambitious teaching practices, which include high-leverage formative assessment practices. Research projects by Briggs and Furtak (this volume) and Wylie and Lyon (this volume) fit within this conceptual framing, contributing, respectively, to the development of a cognitive progression linking formative and summative assessments and a digital tool designed to help teachers engage students in self- and peer assessment. I disagreed with efforts to translate test standards for teachers because learning theory, subject matter knowledge, and pedagogical expertise are much more critical for teacher professional development than knowledge about technical measurement requirements and test formats. Arguments against a measurement orientation for classroom assessment come from the one-third of feedback studies showing negative effects, multiple-choice-only interim tests that do not assess disciplinary practices, the harm of ‘data walls’ that result in public shaming, and data-driven decision-making studies showing the ill effects of accountability cultures. In partnership with disciplinary experts, measurement specialists can make much more valuable contributions in those formal, aggregate applications where rigorous quantifications are needed.