The emergence of and relationship between two notions in personnel evaluation, merit and worth, are traced. How worth should be evaluated, and whether teacher evaluation is worth what it costs are discussed. Limitations of current approaches to teacher evaluation are reviewed, and the potential of a duties-based approach is noted. (SLD)

This essay provides some background on, explanation of, and justification of a theoretical framework for all types of evaluation. This framework is used to connect and underpin the approaches of other contributors to this special issue. A core discipline of evaluation is proposed that ties assorted evaluation fields together. (SLD)