Fraud, like other crime, can best be explained by three factors: a supply of motivated offenders, the availability of suitable targets and the absence of capable guardians-control systems or someone "to mind the store", so to speak (Cohen & Felson 1979).In this, the first of two papers, the authors focus on motivation and other psychological aspects of fraud. They identify a number of psychological correlates of fraud offending, but note that these are by no means unique to fraud, and do not necessarily differentiate fraudsters from law-abiding citizens. The other two factors, opportunities and guardianship, provide more scope for fraud control and are addressed in a companion paper on "red flags", or situational indicia, of fraud risk.