Concern over the potential effects of exposure to endocrine disrupting substances (EDS) has resulted in recommendations for the development of specific endocrine and reproductive tests for assessment and regulation of industrial chemicals and effluents. This document consolidates and summarizes the current approaches taken by international agencies and scientific organizations for testing and screening EDS in mammals and wildlife. The material has been gathered from the Organization for Economic Cooperation and Development meeting reports, U.S. Environmental Protection Agency's Endocrine Disruptor Screening and Testing Advisory Committee and Endocrine Disruptor Screening Program reports, and summaries of various meetings prepared by Canadian and U.S. representatives. There are commonalties between programs of individual countries and the international scientific groups in which they participate. In general, these international scientific organizations have envisioned tiered groups of tests. The first tier is composed of less complex tests and short-term assays (acute exposures) that are very responsive to EDS (and have a low 'false-negative' rate). Higher tiers contain longer tests encompassing partial and full lifecycles of organisms with assessment of functional reproductive and developmental endpoints. Compounds are less expensively screened in the first tier, and move on to more complex and expensive higher-tier tests only if necessary. We document the proposed EDS tests in mammals and wildlife (birds, fish, amphibians and invertebrates) and overview the European Union's approach to EDS research, monitoring and risk assessment. We conclude with a summary of the main recommendations from Canada's interagency workshop to develop priorities and proposed actions for EDS.