This volume provides an overview of the viral vectors and how they are applied to chemogenetic and optogenetic tools to the study of neural circuits. The chapters in this book are organized into three parts detailing (1) viral vectors, (2) vector modifications and applications, and (3) practical advice for the delivery of viral vectors, verification of injection accuracy, and monitoring of transgene expression. In the Neuromethods series style, chapters include the kind of detail and key advice from the specialists needed to get successful results in your laboratory. Authoritative and cutting-edge, Vectorology for Optogenetics and Chemogenetics aims to be a useful practical guide to researches to help further their study in this field.