According to the World Health Organization, Health Literacy (HL) corresponds to the cognitive and social abilities that determine the motivation and ability of individuals to gain access, to understand, and to use information in ways that provide and maintain good health. The development of HL in dentistry came late, and only in the last decade did it reach a level similar to that in the medical area. In dentistry, HL centered on the concept of Oral Health Literacy (OHL), defined as the degree to which individuals have the capacity to obtain, process, and understand basic information on oral health and services that is necessary to make appropriate health decisions. The evidence suggests that people with low HL have worse health status and greater use of medical resources, which results in an increase in costs in the general population. Determinants of the level of OHL include age, level of education, and socioeconomic level. These determinants are reflected in low oral health and in less access to information or less understanding regarding care, pathologies, or dental treatments. The instruments for measuring HL and OHL are mainly aimed at recognizing arithmetic and reading skills, which are not fully related to the ability of the people surveyed to find, understand and use information related to health. OHL is an important issue at the level of health programs, because knowledge of OHL helps in medical practice, in disease prevention and in health promotion. OHL instruments must have validated and demonstrate adequate psychometric properties.