Charles River Laboratories, Inc., is an American corporation specializing in a variety of pre-clinical and clinical laboratory services for the pharmaceutical, medical device and biotechnology industries. It also supplies assorted biomedical products and research and development outsourcing services for use in the pharmaceutical industry. According to its website, its customers include every major pharmaceutical and biotechnology company in the world, major academic institutions and government research centers.

Charles River was founded in 1947, by a young veterinarian who purchased thousands of rat cages from a Virginia farm and set up a one-man laboratory in Boston, overlooking the Charles River. In an effort to fulfill the regional need for laboratory animal models, he bred, fed and cared for the animals and personally delivered them to local researchers. In the last six decades, this one-man laboratory has evolved into a worldwide network. The organisation is constantly expanding their portfolio, and organisational growth has become a continuous strategic effort in anticipating tomorrow’s drug development needs.

The chairman and chief executive officer is James C. Foster.

In October 2003, Charles River Laboratories merged with Inveresk, a UK-owned research company. The company was known then as Charles River Laboratories. Inveresk specialised in clinical research and pre-clinical testing, and their main facilities are in Edinburgh, Scotland. In late 2009, Charles River sold its Clinical Services Division in Edinburgh to Quotient Bioresearch.

In 2010 Charles River Laboratories attempted to acquire WuXi PharmaTech, a China-based contract research organization, but the offer was withdrawn when the deal faced opposition from several large Charles River investors, including Relational Investors, JANA Partners and Neuberger Berman.

Proxy advisory firm RiskMetrics had also recommended that Charles River's shareholders vote against the proposed deal.

In July 2015 the company announced it would acquire Celsis International for $212 million.

In January 2016 the company announced it was set to acquire WIL Research for approximately $585 million in cash.

In June 2016 the company announced it would acquire Blue Stream Laboratories.

The company has been the target of animal rights activists in the UK and US. It owned Shamrock Farm in England's West Sussex which closed in 2000 following a 15-month campaign by animal rights activists.

In 2007, two monkeys at the company’s Sparks, Nevada, facility had their fingers amputated after they were caught in the wiring of their cages while being moved, and a third monkey suffered a cut to its tail.

In 2008, 32 cynomolgus primates, also known as crab-eating macaques, died of overheating at the company's Sparks, Nevada, laboratory after a climate system failure. PETA filed a complaint with the USDA over the incident. The following year, a monkey died at the same facility after being left in their cage as it was going through a hot cage washer. Charles River was fined $14,500 for the two incidents. The company subsequently closed their Sparks facility.

PETA owns $2,000 worth of shares in the company, enough to introduce formal resolutions regarding animal care during the company’s annual shareholder meeting.