Head and neck squamous cell carcinomas (HNSCCs), the 6th most common cancer worldwide, are ideal candidates for early detection given the amenability of the oral cavity for visual inspection, and the availability of recognized premaligant lesions (i.e., leukoplakia, erythroplakia, submucous fibrosis). The major known risk factors for HNSCCs include tobacco and alcohol use. Risk is also increased in HIV patients likely as a result of immunodeficiency. The goal of this study is to estimate malignant transformation rates for HNSCC precursors, and determine whether transformation rates vary by HIV status, grade of dysplasia, site of precursor, age, gender, tobacco and alcohol abuse. We will also perform a pilot feasibility study for retrieval of archived biopsied precursors for future laboratory analyses. A thorough understanding of the natural history of HNSCC precursors may help guide appropriate treatment and follow-up of patients.