Conspectus tools are used to gather collection data for a variety of reasons. Criticisms of the instruments are equally varied. Conspectus users frequently express uncertainty about the accuracy and validity of judgments about collections based on conspectus evaluations. An overview of decision-making research demonstrates that uncertainty is common in most organizational decisions. Authors' interviews with thirteen experienced conspectors resulted in advice and insight into planning a conspectus project, managing group decision making, the role of personal confidence in the validity of decisions, ensuring balance of individual judgment and quantitative data, and selecting appropriate methodologies.