The traditional economic approach to tax evasion does not appear to be particularly successful in explaining the extent of tax compliance. We argue instead that a psychological tax contractnwhich establishes a fiscal exchange between the state and the citizens shapes tax compliance to a large extent. In that respect, a case study of Switzerland is useful because the small size of the cantons and their direct democratic political systems procedurally establish a close exchangenrelationship between taxpayers and tax authorities. In this paper, evidence is discussednon how tax evasion and tax morale in Switzerland evolved over time. In addition, the impact of economic, legal, socio-demographic, psychological and institutional factors on Swiss tax evasion is discussed.