TreeView is a program that allows interactive graphical analysis of the results from Cluster. TreeView reads in matching *.cdt and *.gtr, *.atr, *.kgg, or *.kag files produced by Cluster. We recommend using the Java program Java TreeView, which is based on the original TreeView. Java TreeView was written by Alok Saldanha at Stanford University; it can be downloaded from http://jtreeview.sourceforge.net/. Java TreeView runs on Windows, Macintosh, Linux, and Unix computers, and can show both hierarchical and k-means results.