Massive collection of transgenic Drosophila spreads its wings. Take one complete genome sequence (Drosophila Release 4.3 in this instance), generate interfering RNA transgenes from its predicted protein-coding genes (88% coverage was achieved), and you have a very powerful tool. A team centred on the Institute of Molecular Biotechnology in Vienna has produced and validated a genome-wide tissue-specific Drosophila RNAi library that will facilitate rapid loss-of-function genetic screens, making it possible to study gene functions in essentially any tissue or cell at any stage in the life of the organism. The library will pave the way for work in many fields — including behaviour, sleep, learning, pathology and ageing — that were previously inaccessible to the kind of systematic genetic analysis successfully applied in developmental biology.