The central aim of this work is to establish the basic rationale and clear guidelines for the incorporation of historical baselines into everyday marine resource management and conservation policy and practice. Our approach is to summarise the current status of baselines for fisheries management, pollution abatement, and conservation within the Exclusive Economic Zones of the USA and Australia; define specific criteria for the establishment of rigorous historical baselines that can be used as a frame of reference for management; develop criteria for incorporating historical baselines into regulations, management, and enforcement for sustainable use – while recognising that a return to historically pristine conditions is unrealistic and probably undesirable under most conditions.  Because our analysis enhances the ability to utilize long-term ecological patterns and change as tools in marine management, we are undertaking work of direct benefit to ocean ecosystems and fisheries worldwide.