On Sept. 28, 2005, the National Cancer Institute and the National Institute of Neurological Disorders and Stroke (NINDS) created Rembrandt (Repository for Molecular BRAin Neoplasia DaTa), a joint informatics initiative to molecularly characterize a large number of primary brain tumors and to correlate those data with extensive retrospective and prospective clinical data. Understanding the biology behind these tumors and overlaying this valuable data on clinical data will provide clues to discover new therapies.