Adeno-associated virus (AAV) forms the basis of one of the most promising and most versatile vector systems for therapeutic human gene transfer, owing to a unique combination of apathogenicity and low immunogenicity, paired with high amenability to genetic engineering and repurposing of the viral capsid and genome. This presentation will introduce an assortment of key technologies for targeted modification and directed evolution of critical AAV components, with a particular focus on their application on the large scale and on the high-throughput selection of ensuing capsid or promoter libraries in animals.