GenePattern provides access to a broad array of computational methods used to analyze genomic data. A simple application interface gives a broad audience access to a growing repository of analytic tools for genomic data, while an API supports computational biologists. Workflow supports multidisciplinary genomic research programs and is designed to encourage rapid integration of new techniques. Extensible architecture makes it easy for computational biologists to add analysis and visualization modules, which ensures that GenePattern users have access to new computational methods on a regular basis. GenePattern has been publicly released since January of 2003 and has over 15,000 users at over 2,200 institutions worldwide. It won the Bio-IT World Best Practices Editors choice award in 2005. The Broad Institute hosts an instance of GenePattern for public use