NLRS is a joint Canadian/Norwegian study of the pace and extent of recovery of lake ecosystems from acidification. Twenty-one oligotrophic lakes within Killarney Park, Ontario were selected as the principal Canadian sites for this study. NLRS objectives for Killarney included: testing of new biomonitoring techniques, assessment of multiple stressor effects on recovery, and development of biological endpoints for critical load modelling. Sampling included: phytobenthos, phytoplankton, pelagic zooplankton, littoral zooplankton, sublittoral chironomids, and fish, as well as sediment cores for paleolimnological assessment of pre-industrial biotic communities. Strong statistical models were developed relating biotic composition to water quality variables. Prediction of future recovery will require additional understanding of the effects of differential colonization rates, climate variability, and the impact of unique events such as the arrival of an exotic species. Recovery proved to be best measured against modern reference data from circumneutral lakes rather than against historic data from acidified systems.