A method, system, apparatus, and program product for displaying a program slice diagram, which represents source code. The program slice diagram includes a directed graph that has multiple nodes and arcs connecting the nodes. Nodes can correspond to statements within a selected subroutine of the source code, variable references outside the subroutine, or calls made to other subroutines that are considered part of the program slice. Arcs represent data flow dependencies between the nodes. In another aspect, the invention encompasses a software environment for visualizing source code that includes a code browser, a block-level abstract syntax tree viewer, a program slice browser, and a template viewer. This software visualization environment is integrated, allows cross-referencing between its components, and is coupled with a performance visualization environment.