Engineers have always had to make professional judgements but these decisions are now being scrutinised and challenged as never before. Examples range from risk assessments to tender evaluations and the delivery of 'best value'. This paper explains that professional engineering judgements are an expression of responsibility in which our values lead to a preference. It then shows how such judgements can be measured and analysed using the principles of soft performance management and, more importantly, what actions we should take as result. Four case studies demonstrate how the principles can be put into practice.