A short form of the 60-item computer-based orthographic processing assessment (long-form COPA or COPA-LF) was developed. The COPA-LF consists of five skills, including rapid perception, access, differentiation, correction, and arrangement. Thirty items from the COPA-LF were selected for the short-form COPA (COPA-SF) based on cognitive diagnostic modeling (CDM) analyses. Both parametric and nonparametric CDM and correlational analyses were conducted with the responses of 74 U.S. second-grade students on the COPA-SF. Results supported five skills of orthographic processing represented on the COPA-SF. Concurrent and convergent validity evidence was found for the COPA-SF. Overall, the findings suggest that the COPA-SF is a time-efficient, reliable, multidimensional measure of orthographic processing.