The UK veterinary profession has an elevated risk of suicide. The ability to measure the psychological health of this occupational group is an important first step towards suicide prevention. The aim of this research was to assess the suitability of the 14-item Warwick-Edinburgh Mental Well-being Scale (WEMWBS) in this context. The psychometric properties of data quality, scaling assumptions, targeting, reliability and validity were rigorously evaluated by the complementary application of traditional and modern psychometric methods to data from two large cross-sectional samples of the veterinary profession (n = 1796 and n = 8829) derived from independent postal surveys. Where possible, the findings were cross-validated between samples. External construct validity was assessed by testing a priori hypothesised associations between WEMWBS scores and other measures of psychological health or psychosocial work characteristics. Internal construct validity was examined using traditional factor analytic techniques and Rasch analysis. The WEMWBS did not show floor or ceiling effects. As hypothesised, scores were negatively associated with anxiety and depressive symptoms and suicidal ideation. Data for the original 14 items deviated significantly from Rasch model expectations (chi-square = 558.2, df = 112, p = < 0.001, PSI = 0.918). A unidimensional 7-item scale (Short WEMWBS, SWEMWBS) with acceptable fit to the model (chi-square = 58.8, df = 56, p = 0.104, PSI = 0.832) was derived by sequential removal of the most misfitting items. Fit statistics for SWEMWBS were consistent across four further random subsets of data drawn from both samples. Interval-level measurements on SWEMWBS retained associations with scores on comparator instruments. The analyses provided a range of evidence of the psychometric properties of WEMWBS and SWEMWBS, consistent with published results for general population samples. The measurement invariance of SWEMWBS between samples of this occupational group and the general population was supported. SWEMWBS has robust measurement properties which support its suitability as an overall indicator of population mental health and well-being in the UK veterinary profession.