The purpose of the NIAID Virology Quality Assurance (VQA) program is to provide a comprehensive quality assessment program for virologic assays for HIV, and other viral pathogens, performed on samples from subjects enrolled in NIAID-sponsored multisite clinical studies. The VQA program ensures the validity and inter- and intra-laboratory comparability of virologic laboratory data obtained from NIAID-supported clinical trials and HIV natural history studies by providing laboratories with proficiency testing panels and real-time assay run controls and analyzing proficiency panel and assay run data from each laboratory. The VQA program also implements standards of performance for existing and state-of-the-art new virologic assays, develops and tests biostatistical methods relating to the assays, and acquires, tests, stores and dispenses quality control materials and reagents.