Background The outcomes framework for the new public health and mental health strategies in England (Healthy Lives Healthy People and No Health without Mental Health) both propose monitoring positive mental health. The Office of National Statistics is currently consulting on approaches to the measurement of wellbeing. Public mental health projects and interventions at local level require measurement of mental wellbeing The Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS) is a possible candidate.

Methods WEMWBS was developed in 2007 following UK evaluation of a longer mental wellbeing measure (Affectometer 2), a review of the literature and the support of a multidisciplinary expert panel. It comprises 14 positively worded items relating only to positive attributes of mental health. Quantitative validation has been undertaken in student (n=354) and adult (16 yrs plus; n=2075) UK populations and mixed method evaluations in teenage (13–15 years) and UK dwelling Pakistani and Chinese groups.

Results Initial evaluation showed good content validity; confirmatory factor analysis supported a single factor hypothesis (GFI =0.93, AGFI=0.8, RMSEA=0.055); Cronbach's α (0.89) suggested the possibility of item redundancy; item total correlations ranged from 0.52 and 0.80; the distribution was near normal; there were no floor or ceiling effects; test-retest reliability was high (0.83) and the scale discriminated population groups in a way which was consistent with results of other surveys. WEMWBS correlated with criterion scales to the expected extent and in the expected direction. WEMWBS was not RASCH compatible but a reduced 7 item scale, Short Warwick-Edinburgh Mental Wellbeing Scale (SWEMWBS) was resolved which met RASCH model requirements. Quantitative evaluations showed the scale to be robust in Chinese and Pakistani groups and in teenagers. Qualitative evaluation broadly supported these findings and offered insights into mental wellbeing across different groups. WEMWBS is sensitive to change in evaluations of diverse public health interventions and programmes including general lifestyle interventions and parenting programmes. It is also sensitive to change in psychiatric populations.

Conclusions In addition to offering rigour for research and evaluation in public mental health, WEMWBS' positive focus offers a developmental perspective, helping to orientate policy makers, programme participants and survey respondents towards mental wellbeing and enabling identification of protective and promoting factors.