As part of a substance abuse prevention project, a measure was developed in both English and Spanish to measure levels of acculturation among members of a Latino youth population for later comparison of acculturation with high-risk behaviors. The Latino Youth Acculturation Scale (LYAS) consists of 23 items. Eleven items deal with language use of the respondent; six items deal with television viewing, music, and eating habits; and six items focus on cultural activities. The LYAS was administered to students in the fifth through eighth grades at two Chicago (Illinois) elementary schools in predominantly Latino neighborhoods. Usable surveys were obtained from approximately 650 youths, of whom 33 percent were first-generation in the United States. Forty percent of the respondents self-identified themselves as Puerto Rican, 28 percent as Mexican, 5 percent as both Mexican and Puerto Rican, and 7 percent as other Latino ancestry. A principal components analysis with oblimin rotation performed on the 23 items produced 4 factors with eigenvalues greater than 1.0 that accounted for 69 percent of the total variance. These factors were: (1) family identity; (2) self/peer identity; (3) customs; and (4) food. The LYAS appears to measure levels of acculturation in terms of these four factors. It has great utility because it is easy to administer, is written in Spanish and English, and was developed for more than a single Latino group. Three tables present study data, and two figures illustrate the degree of acculturation. An appendix contains the LYAS. (SLD)