This book covers a gap in legal literature, offering critical reflections on the «European Crowdfunding Service Providers for Business» Regulation (ECSPR). The analysis approaches issues of financial stability, market adaptation and protection of all parties in Financial Return (FR) crowdfunding transactions (crowdfunders, issuers and service providers) from an international and European point of view. The first part of the study introduces the regulatory framework surrounding FR-crowdfunding. It proposes a theory of three fundamental EU principles of financial regulation which govern the regulation, supervision and enforcement of FR-crowdfunding. The second part of the study applies the fundamental principles introduced in Part I to support the strengthening of the ECSPR, the implementation of complementary FR-crowdfunding models and the enhancement of macro-prudential supervision at the EU level in cases of rescuing and restructuring state aid.