The 7-item adult version of the Personal Wellbeing scale (Cummins et al. Social Indic Res 64:159-190, 2003) was administered to two samples of adolescents aged 12-16 in Brazil (N = 1,588) and Spain (N = 2,900), and to a sample of adolescents aged 14-16 in Chile (N = 843). The results obtained were analyzed to determine its psychometric characteristics when used with adolescents in the three different countries and to check whether two additional items would improve its qualities. Results reveal that the new PWI-9 version worked well with the adolescents in the three countries, improving some of the qualities of the PWI-7. One of the added items, satisfaction with oneself, appears to be a major contributor to unique explained variance when regressed on the single-item of overall life satisfaction (OLS). The model we present using structural equations shows good fit statistics for the factor structure, with both 7 and 9 items. Separate in-country analyses demonstrate that cultural context has a strong influence on correlations and saturations between the studied variables and also on the explained variance. Probably related to this fact, the Model fit structure is good in Brazil (with a low PWI variance accounted for by its predictors) and Spain (medium), but rather modest in Chile, where data show a high proportion of the PWI variance accounted for by its predictors. However, a multi-group factor analysis among the three countries restricting saturations to 1 in each country in order to make data comparable across countries still show a good fit of the proposed model for both PWI-7 and PWI-9.