Evaluative criteria define a “high quality” or “successful” evaluand and provide the basis for judgment of merit and worth, yet they are often assumed and implicit in the evaluation process. This article presents an empirically supported model that describes and integrates two aspects of criteria: domain and source. Domain identifies the focus or substance of a criterion, while source describes the individual, group, or document from which it is drawn. Developed from a synthesis of evaluation literature and empirical analysis of evaluation reports, the model defines 11 criteria domains and 10 sources and reveals the relationships among them. In this integrated model, the two dimensions can be used together as a thinking tool to guide evaluators in specifying criteria, in empirical research on the valuing process, and as a conceptual framework and language for theorists prescribing criteria selection.