This handbook focuses on the key issues that continue to hinder the formal development of cryptocurrencies as a mainstream financial asset. It primarily examines reputationally damaging events, particularly those related to illicit behavior. The goal of the handbook is to determine whether some of these events could be mitigated by improved or at least coordinated international regulation. The handbook will be useful for specialist technical audiences such as legal, accounting and financial practices. It will also be beneficial for upper level masters and research students in economics, law, accounting, taxation, investment and portfolio management.