The key concepts, dimensions and decisions involved in assessing communication competence are reviewed. Competence assessment depends first upon locating competence in skills or abilities, or in impressions of those skills and abilities. The criteria of competence, such as accuracy, appropriateness and effectiveness, also require inclusion. A taxonomy of communicative competence measurement dimensions is explicated, and its implications for developing and validating competence assessments are explored. The three basic dimensions are locus, directness and generalization. Key issues and challenges are identified through the exploration of the questions: What, who, where, how, and why assessments are being made.