No / Wellbeing is a complex construct and to date there has been great inconsistency across measures of wellbeing with respect to their theoretical foundations, dimensions, composition, and psychometric properties. The need for wellbeing measures that have robust epistemological and ontological frameworks and sound psychometric properties is evident as a basis for effective care planning, outcome evaluation and research. The following paper describes the development and psychometric evaluation of the Wellbeing Evaluation Scale (WES), long and short forms, from an analysis of data drawn from a representative population of 203 adults aged 55 years and over. Following an initial pilot study (n = 98), a repeated investigation involved a representative sample of 203 adults over the age of 55 who were recruited from the West Midlands for this study. The findings suggest that the WES is a reliable, valid, and representative measure of wellbeing in adults over 55. It is concluded that the WES can be considered as a reliable tool for the purposes of assessment, care planning and research.