Clinical Reference Laboratory (CRL) is a privately held clinical testing laboratory that provides testing services for drugs of abuse, genetics, clinical trials, and pathology. CRL is one of the largest privately held testing laboratories in the United States. The company was founded in 1979 and is headquartered in Lenexa, Kansas. CRL has a network of over 4,000 collection sites and provides testing services to clients in all 50 states and internationally. CRL is accredited by the College of American Pathologists (CAP) and the Substance Abuse and Mental Health Services Administration (SAMHSA).