Developments in technology have not only transformed aspects of our daily life, but they have also impacted the way in how illicit transactions are organised, such as illicit drug supply and demand. This book focuses on illicit drug transactions through drug marketplaces on the dark web, also called cryptomarkets. The dark web is an encrypted, small part of the internet not searchable by regular search engines. These drug cryptomarkets offer an unprecedented opportunity to study a drug market and to monitor new trends in drug supply and demand. International research has provided some general insights into the profile, experiences and motivations of drug cryptomarket vendors and buyers. This research has however indicated that national differences exist regarding the different variables that relate to cryptomarket use and prevalence. Therefore, in 2019, the Belgian Science Policy Office (BELSPO) commissioned and financed CRYPTODRUG shedding a first, yet necessary, light on illicit drug trade on cryptomarkets from a Belgian perspective. From the alley to the web. Belgian involvement on drug cryptomarkets discusses these CRYPTODRUG results. The book does not only focus on the profile of Belgian vendors selling illicit drugs on drug cryptomarkets, but also provides a first insight into the experiences and motivations of Belgian cryptomarket buyers. Charlotte Colman is assistant professor of Drug Policy and Criminology at Ghent University and member of the Institute for International Research on Criminal Policy (IRCP) Antoon Bronselaer is assistant professor of Computer Science Engineering at Ghent University and member of the research group Database, Document and Content Management (DDCM) Marie-Sophie Devresse is a professor of Criminology at UClouvain and member of the Interdiciplinary Research Centre on Deviance and Penality (CRID&P) Geert Slabbekoorn was a researcher at the Institute for International Research on Criminal Policy (IRCP), Ghent University during the CRYPTODRUG project