The company has two segments, Research Models and Services (RMS) and Preclinical Services (PCS), which includes Phase I clinical services. The RMS segment supplies research models to the drug development industry, including genetically and virally defined purpose-bred rats and mice, and related services to support their use. Charles River Laboratories is a leading provider of animal models for laboratory testing, with facilities located on three continents. Its mission is to improve the quality of people's lives through excellent science and a strong sense of purpose.