The aims of this study are: a) to devise a questionnaire to evaluate positive mental health following the conceptual model proposed by Jahoda (1958), and b) to analyse the instrument’s psychometric properties in order to assess the hypothesized conceptual model. The sample comprised 387 students from the Nursing School at the University of Barcelona. The general results point to a model of positive mental health that differs from Jahoda’s. The psychometric analyses of the questionnaire were favorable: the homogeneity index of the items was above 0.25; the alpha coefficient of the global scale was 0.91 and the test-retest reliability coefficient 0.85; the correlation between the Positive Mental Health Questionnaire and Goldberg’s General Health Questionnaire (Goldberg, 1972) was -0.41; the six factors extracted from the exploratory factor analysis explained 46.8% of total variance. However, further research is necessary before the psychometric results of the questionnaire can be generalized and the new model of positive mental health confirmed.