A 2-phase study was conducted to develop a culturally informed measure of psychosocial stress for adolescents: the Hispanic Stress Inventory--Adolescent Version (HSI-A). Phase 1 involved item development through the collection of open-ended focus group interview data (n = 170) from a heterogeneous sample of Hispanic youths residing in the southwest and northeast United States. In Phase 2, we examined the psychometric properties of the HSI-A (n = 1,651), which involved the use of factor analytic procedures to determine the underlying scale structure of the HSI-A for foreign-born and U.S.-born participants in an aggregated analytic approach. An 8-factor solution was established, with factors that include Family Economic Stress, Acculturation-Gap Stress, Culture and Educational Stress, Immigration-Related Stress, Discrimination Stress, Family Immigration Stress, Community and Gang-Related Stress, and Family and Drug-Related Stress. Concurrent, related validity estimates were calculated to determine relations between HSI-A and other measures of child psychopathology and behavioral and emotional disturbances. HSI-A total stress appraisal scores were significantly correlated with both the Children's Depression Inventory and the Youth Self Report (p < .001). Reliability estimates for the HSI-A were conducted, and they yielded high reliability coefficients for most factor subscales, with the HSI-A total stress appraisal score reliability alpha at .92.