Abstract: A Portal Assessment Design System includes a system for designing assessment models and assessments (e.g., standardized tests). In assessment design, specifications are organized around three basic elements: 1) what knowledge, skill or abilities are important to measure; 2) what is necessary evidence of that knowledge, skill or ability; 3) what performance situations are needed to elicit the required evidence from students and other assessment users. The system includes three modules (i.e., Domain Analysis, Domain Modeling, Conceptual Assessment Framework), each of which targets a specific phase of the design process, for designing an assessment in accordance with the three basic elements. The sequence of modules represents the structure of a design process that helps assessment developers work through successive stages or phases of assessment design, from the gathering of raw information to the creation of a complete set of specifications for an assessment product.