The Organization for Economic Cooperation and Development (OECD) published a report entitled Alternative Testing Strategies in Risk Assessment of Manufactured Nanomaterials: Current State of Knowledge and Research Needs to Advance Their Use. Experts from academia, industry, public interest groups, and government researched, analyzed, and discussed how alternative models could be used to advance the risk analysis of manufactured nanomaterials. The objectives were to identify how alternative testing strategies could be used in a risk analysis context to inform human health, ecosystem health, and exposure data needs for manufactured nanomaterials in the near term and longer term, and identify research needs to support the development of these strategies in the near future. To develop the report, a number of activities were organized, including a symposium, a case study on alternative methods in safety testing, a state-of-the-science report, and three white papers. These results were further discussed as background materials for developing recommendations to advance knowledge and fill key gaps in understanding. The report states that one conclusion was that alternative testing strategies are now being used for screening, and that, in the near term, alternative testing strategies could be developed for use in read-across or categorization decision making within certain regulatory frameworks. According to the report, experts recognized that leadership is required from within the scientific community to address basic challenges, such as standardization of materials, techniques, and reporting, designing experiments relevant to realistic outcomes, and the coordination and sharing of large-scale collaborations and data. OECD expects that the conclusions from the report can contribute to the development and implementation of relevant alternative testing strategies for manufactured nanomaterial testing that will expedite the ability to identify high-risk manufactured nanomaterials, and lead to more rapid, cost-effective, and reliable safety testing for specific risk management decision contexts.