Professional evaluation is a market-based activity in which economic c
onsiderations play a dominant role. But are there ever professional re
asons for turning down an evaluation contract? Considering how evaluat
ions can promote either guild maintenance interests or societal improv
ement interests illuminates several dilemmas in the proper conduct of
evaluation and suggests the need for greater explicit attention to wha
t it means for the evaluation profession to contribute to the public i
nterest.