During 2011–2013, Professor Magnus Ulväng and Professor Iain Cameron organized a series of seminars and two conferences at the Faculty of Law of Uppsala University, bringing together a number of distinguished researchers in criminal law. The themes were criminalization and sanctions. The two themes are linked: we are seeing a development in many countries towards expanded criminalization and stiffer penalties, despite the lack of empirical evidence that tougher sentences have any significant impact on crime. Amongst the different topics covered during the seminar series were the relationship between vengeance and the criminal law, the principle of ultima ratio, the development of criminalization in EU law, the evolution and justification of the system of Ordnungswidrigkeit and the role of moral theories in criminalization. This volume collects the essays which grew out of the papers presented during the seminar series.