'Combatting' irregular migration is one of the key challenges to migration management at EU level. The present book addresses perhaps one of the most pressing structural problems regarding the EU's return policy: the low return rate of irregularly staying migrants. Even though Member States must issue a return decision according to the Return Directive, only 40% of such decisions are enforced. Despite all of the political and legal efforts made, the EU is not making any significant progress in enforcing the rules laid down in the Return Directive. Possible solutions can be found in the national legal frameworks of selected EU Member States, which is why Austria, Germany and Spain are examined comparatively. These three Member States use, inter alia, differentiated systems of regularisation (i.e. the award of residency rights) to combat the problem of irregularly staying migrants. Regularisations constitute an effective alternative to returns, because they terminate the irregular residence of migrants, not through deportation, but rather by granting a right of residence. Hence, this book defends the following thesis: EU regularisations supplementing the present return policy are more effective at combatting irregular migration at EU level.