The purpose of this study was to derive and validate a domain of teacher proficiency
indicators in formative, diagnostic classroom assessment, and to demonstrate the utility of
the overall domain and sub-domains as a framework for designing future instruments. The
domain was envisaged as a behavioral-attitudinal construct and derived using an emergent,
two-stage design with mixed methods. The resulting domain and sub-domains suggest a
theory on a continuum of teacher change in classroom assessment practices. Implications
for future research on teacher development in diagnostic assessment skills in the U.S. and
international education settings, are discussed.