An Illinois-based international medical society composed primarily of pathologists (known widely by the acronym “CAP”). In transfusion medicine, interactions with CAP are primarily through accreditation and proficiency assessment. Transfusion services, like the rest of the laboratory, are inspected by CAP (most commonly by volunteer physicians and lab scientists from other laboratories) every two years. CAP has been granted “deemed status” with the Centers for Medicare and Medicaid Services (CMS), so CAP inspection/accreditation serves as a replacement for CMS inspections. In addition, CAP is the largest provider of laboratory proficiency samples, which labs use to assess their ability to provide accurate results, in accordance with CLIA regulations.