This dissertation sought to investigate two interrelated issues: first, to explore the ‘basic legitimation demands’ of operators in the Maltese financial services sector; second, and arising from the first, to explore the influence of legitimacy perceptions on the behaviour of operators. Legitimacy – the recognition of power as morally valid – is an important topic to researchers across many disciplines and to policy makers. Unlike other disciplines, criminology has been a latecomer to legitimacy research, with Tom Tyler’s Why People Obey the Law being the watershed moment. Evidence in criminology shows legitimacy perceptions correlate with actual or intended compliance with laws and cooperation with legal authorities. However, a number of criticisms have arisen including how best to conceptualise and operationalise legitimacy. Some have argued that while criminologists theorise legitimacy as a social-scientific concept, their empirical analysis has not reflected this theorisation. Legitimacy scales are developed in ways that do not fully reflect the socially constitutive nature of legitimacy. Drawing on methodological insights from prisons research, this dissertation attempts to address this gap in the wider criminology literature. It does so in the context of the Maltese financial services regulator. In focusing on the Maltese financial services regulator, the dissertation also promises contributions to fields beyond criminology – for example, in sociology, management and organisational studies, and political science. How do operators in the Maltese financial services sector construct the legitimacy of the regulator? What basic legitimation demands do they make of the regulator? How do their views about the legitimacy of the regulator influence their self-reported behaviour and intentions toward the regulations? A mixed-methods research design was used to answer these questions. A qualitative component involved interviews with 49 Maltese financial services participants to discover what mattered to operators licensed by the Malta Financial Services Authority (MFSA) and why. Based on the interview data, a regulatory legitimacy scale was developed and tested among a sample of 226 Maltese financial services operators. Confirmatory factor analysis identified a three-factor legitimacy model comprising rule of law, distributive fairness and responsiveness. Further analysis showed that perceived legitimacy of MFSA was strongly correlated with positive attitudes to compliance.