This paper presents findings from a study investigating the application of a multi-source measurement approach to the assessment of higher order competencies in the public service industry. The aim of the project was to develop and validate strategies to synthesise multiple sources of evidence to inform judgements of workplace competence. The methodology adopted integrated developments in two fields of study, performance appraisals and psychometrics. Seventy-five candidates were assessed using a combination of self-assessment, observer reports, interview and portfolio. Rasch analysis techniques proved to be useful for synthesising evidence gathered from a range of sources, and can be used to inform the decision making process.