We announce the release of Reconstruct Ancestral State in Phylogenies (RASP), a user-friendly software package for inferring historical biogeography through reconstructing ancestral geographic distributions on phylogenetic trees. RASP utilizes the widely used Statistical-Dispersal Vicariance Analysis (S-DIVA), the Dispersal-Extinction-Cladogenesis (DEC) model (Lagrange), a Statistical DEC model (S-DEC) and BayArea. It provides a graphical user interface (GUI) to specify a phylogenetic tree or set of trees and geographic distribution constraints, draws pie charts on the nodes of a phylogenetic tree to indicate levels of uncertainty, and generates high-quality exportable graphical results. RASP can run on both Windows and Mac OS X platforms. All documentation and source code for RASP is freely available at http://mnh.scu.edu.cn/soft/blog/RASP.