Isolation by Distance Web Service (IBDWS) is a user-friendly web-based tool for analyzing population genetic data to detect patterns of isolation by distance (IBD). IBDWS allows users to perform various statistical tests, including Mantel tests, reduced major axis (RMA) regression, and calculation of FST between population pairs. It also generates publication-quality scatter plots and provides basic summary statistics. The software is hosted at http://phage.sdsu.edu/~jensen/ and documentation is available at http://www.bio.sdsu.edu/pub/andy/IBD.html. The source code is available on Source Forge at http://sourceforge.net/projects/ibdws/. IBDWS is a major expansion and upgrade of the standalone IBD program, which was originally written in C and compiled for Windows and Macintosh. IBDWS includes features such as analysis of raw data, statistical tests, a simple form interface, analysis selection, publication quality graphics, and rapid analysis. It is written in C++, compiled with the Unix g++ compiler, and runs on a server using Apache 2.0.50 and Fedora Linux. Postscript file plotting capability is implemented using CGraph, a C++ plotting library. The UNIX command "convert" is called by IBDWS to create a JPEG for web-based viewing from the postscript file. Both files are held on the server for 24 hours until routine deletion. IBDWS performs four primary functions: generating standard summary statistics from raw data, generating scatter plots of genetic vs. geographic distance, assessing the relationship between genetic and geographic distance matrices, and performing statistical analyses of the IBD relationship. It also includes features for log-transformation of genetic and geographic distances, and provides an interface that switches among the four possible scatter plots. IBDWS is designed to be a substantial expansion of the previous PC-based versions of IBD, providing geneticists with a simple interface, multiple statistical calculations, rapid analysis, and high-quality graphics. It will be useful to a significant number of molecular ecology, conservation genetics, population genetics, and genomics researchers, and will be updated with newer analyses in the future. IBDWS is currently hosted at http://phage.sdsu.edu/~jensen/. Documentation of the statistical calculations and biological context are available on IBD's original website at http://www.bio.sdsu.edu/pub/andy/IBD.html. The programming source files have been made available at http://sourceforge.net/projects/ibdws/ under the GPL (GNU Public License).Isolation by Distance Web Service (IBDWS) is a user-friendly web-based tool for analyzing population genetic data to detect patterns of isolation by distance (IBD). IBDWS allows users to perform various statistical tests, including Mantel tests, reduced major axis (RMA) regression, and calculation of FST between population pairs. It also generates publication-quality scatter plots and provides basic summary statistics. The software is hosted at http://phage.sdsu.edu/~jensen/ and documentation is available at http://www.bio.sdsu.edu/pub/andy/IBD.html. The source code is available on Source Forge at http://sourceforge.net/projects/ibdws/. IBDWS is a major expansion and upgrade of the standalone IBD program, which was originally written in C and compiled for Windows and Macintosh. IBDWS includes features such as analysis of raw data, statistical tests, a simple form interface, analysis selection, publication quality graphics, and rapid analysis. It is written in C++, compiled with the Unix g++ compiler, and runs on a server using Apache 2.0.50 and Fedora Linux. Postscript file plotting capability is implemented using CGraph, a C++ plotting library. The UNIX command "convert" is called by IBDWS to create a JPEG for web-based viewing from the postscript file. Both files are held on the server for 24 hours until routine deletion. IBDWS performs four primary functions: generating standard summary statistics from raw data, generating scatter plots of genetic vs. geographic distance, assessing the relationship between genetic and geographic distance matrices, and performing statistical analyses of the IBD relationship. It also includes features for log-transformation of genetic and geographic distances, and provides an interface that switches among the four possible scatter plots. IBDWS is designed to be a substantial expansion of the previous PC-based versions of IBD, providing geneticists with a simple interface, multiple statistical calculations, rapid analysis, and high-quality graphics. It will be useful to a significant number of molecular ecology, conservation genetics, population genetics, and genomics researchers, and will be updated with newer analyses in the future. IBDWS is currently hosted at http://phage.sdsu.edu/~jensen/. Documentation of the statistical calculations and biological context are available on IBD's original website at http://www.bio.sdsu.edu/pub/andy/IBD.html. The programming source files have been made available at http://sourceforge.net/projects/ibdws/ under the GPL (GNU Public License).