The principal conclusion of a workshop in October 2005 at RIVM (Bilthoven, The Netherlands) on the assessment of field studies with pesticides for authorization is that the lack of a definition of acceptability of effects is recognized as a problem by all stakeholders: Industry, risk assessors, and regulators. Because of this lack of definition in the legislation, it is unclear what critical effect values should be assessed in field studies. Despite the extensive documentation on field study performance, the decision making is not based on justifiable scientific opinions or publicly shared values but on technical limitations of the test design instead. In the workshop, research was identified that should result in a scientific basis for value judgments applied in decision making.