The development of measures for assessing oral health status is essential to the evolution and maturation of a scientific knowledge base in geriatric dentistry. The literature suggests a high prevalence of dental diseases in older adults, yet valid and reliable instruments to assess the impact of oral diseases on older individuals or populations are lacking. This paper describes the rationale for and the development of the Geriatric Oral Health Assessment Index (GOHAI), a self-reported measure designed to assess the oral health problems of older adults. Following a review of the literature and consultation with health care providers and patients, a pilot instrument was developed. The GOHAI was initially tested on a convenience sample of 87 older adults. A revised instrument was then administered to a sample of 1755 Medicare recipients in Los Angeles County. The GOHAI demonstrated a high level of internal consistency and reliability as measured by a Cronbach's alpha of 0.79. Associations of the GOHAI with a single-item rating of dental health and with clinical and sociodemographic supported the construct validity of the index. Having fewer teeth, wearing a removable denture and perceiving the need for dental treatment were significantly related to a worse (lower) GOHAI score. Respondents who were white, well educated, and with a higher annual household income were more likely to have a high GOHAI score, indicating fewer dental problems. Additional applications of the GOHAI are necessary to further evaluate the instrument's validity and reliability, and to establish population norms of oral health in older adult populations as measured by the GOHAI.