Clinical and Laboratory Standards Institute document GP29-A2--Assessment of Laboratory Tests When Proficiency Testing Is Not Available; Approved Guideline--Second Edition offers methods to assess test performance when formal proficiency testing (PT) programs (also known as external quality assessment [EQA] programs) are not available. The guideline includes examples with statistical analyses. This document is intended for use by laboratory managers and testing personnel in traditional clinical laboratories as well as in point-of-care and bedside testing environments.