This study was designed to assess the validity of the Spanish Burnout Inventory (SBI) in a sample of Mexican teachers. Methodology. The sample consisted of 505 secondary school teachers from 26 schools in the city of Aguascalientes, Mexico. By gender, 46% were men and 54%, women. The Spanish Burnout Inventory was applied, using the version for professionals working in education (SBI-ED). This instrument contains 20 items distributed into four dimensions: Enthusiasm for the job (five items) (alpha = .72), Psychological exhaustion (four items) (alpha = .87), Indolence (six items) (alpha = .67) and Guilt (five items) (alpha = .78). Low scores on Enthusiasm for the job and high scores on Psychological exhaustion, Indolence and Guilt indicate high levels of burnout. Data were subjected to confirmatory factor analysis using the LISREL 8.30 program. All relationships between items and dimensions were significant. The hypothesized four-factor model yielded an adequate data fit for the sample (Chi((164))(2) = 472.25, p < .001, AGFI = .96, RMSEA = .061, NNFI = .96, CFI = .97 and PNFI = .82). These results confirmed the hypothesis. Cronbach's alpha was satisfactory for all subscales. The results of this study contribute to the psychometric validation of the four-dimensional theoretical model from which the questionnaire originates and the transnational validation of the instrument. The results also make it possible to conclude that the SBI-ED is a reliable, valid instrument for evaluating burnout in Mexican teachers. The results offer a psychometrical instrument for the diagnosis of burnout, and they can contribute to the prevention of job stress in educational settings by facilitating studies on the prevalence of burnout.
