Modern light microscopes use digital cameras, motorized stages, shutters, filter wheels, etc., that need to be controlled by computer software. Various commercial solutions exists, all of which have shortfalls. The Manager software application is open source, freely available software for microscope automation written for and by scientists that runs on Windows, Mac OS X, and Linux. It provides an easy-to-use interface through which most microscope hardware can be controlled making it simple for scientists to carry out experiments using equipment from different vendors. The software is used at about 2000 microscopes world-wide, and provides significant savings to the NIH since individual copies of commercial alternatives cost $5-15k. Manager also provides a hardware abstraction layer that is used by scientists with programming abilities to automate their microscope hardware in novel and creative ways. The open source nature of this project not only makes it possible to see exactly how acquisition protocols are carried out (which is important in research), but also attracts many code contributions from industry and academia. Many companies already make sure that their equipment works within Manager and maintain the source code for their equipment in the Manager source code repository. More than 50 programmers have contributed code, a number that continues to rise. This grant will be used to continue stewardship of these many code contributions, regularly release user-friendly installers for the software, improve documentation, address bug reports, etc. It will also be used to add novel capabilities to the software such as live STORM/PALM imaging, structured illumination-based optical sectioning, and photo-bleaching/photo-activation using digital mirror devices. In addition, integration with existing open source microscopy-related software packages will be improved. Manager, the world's only comprehensive open source software package for microscope automation. Available for free download, Manager provides a substantial cost savings for NIH and encourages the application of novel, innovative techniques in light microscopy. Manager software is used to control a growing number of microscopes (currently > 2,000) world-wide.