While there is broad agreement that resources are valuable and need to be used wisely and sustainably, there is less agreement on the definitions of such terms as “wisely” and “sustainable,” meanings that evolve within the context of identifying society’s objectives and creating the mechanisms and policies to achieve them. Professor Costello works in this area, focusing on the economics of environmental regulation and natural-resource management under conditions of uncertainty (inaccurate, unavailable, or contradictory information), with a particular emphasis on the value and effect of information on management decisions. Correlate to this is his interest in adaptive-management programs that have a learning component intended to resolve uncertainty. He has applied this perspective to studies in biological diversity, introduced species, regulation of polluting industries, and marine policy.