In 2000, the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) was congressionally established, with representatives from Federal regulatory and research agencies that require, use, generate, or disseminate toxicologic and safety testing information. For over 15 y, ICCVAM and the National Toxicology Program's Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) have worked together to promote the development, validation, and regulatory acceptance of test methods that replace, reduce, or refine the use of animals in regulatory testing. In 2013, both NICEATM and ICCVAM underwent major changes to their operating paradigms, to increase the speed and efficiency of regulatory approval and industry adoption of 3Rs testing methods within the United States and internationally. Accordingly, increased emphasis has been placed on international activities, primarily through interaction with the Organization for Economic Cooperation and Development and participation in the International Cooperation on Alternative Test Methods. In addition, ICCVAM has committed to increasing public awareness of and transparency about federal agencies' 3R activities and to fostering interactions with stakeholders. Finally, although it continues to support ICCVAM, NICEATM's work now includes validation support for Tox21, a collaboration aimed at identifying in vitro methods and computational approaches for testing chemicals to better understand and predict hazards to humans and the environment. The combination of more efficient operating paradigms, increased international collaboration, improved communication and interaction with stakeholders, and active participation in Tox21 likely will substantially increase the number of 3Rs methods developed and used in the United States and internationally.