The present invention provides inserting and deleting a breakpoint in a parallel processing system. A breakpoint is inserted in a module loaded into the execution environment of an attached processor unit. The breakpoint can be inserted directly. Furthermore, the unloaded image of the module can also have a breakpoint associated with it. The breakpoint can be inserted directly into the module image, or a breakpoint request can be generated, and the breakpoint is inserted when the module is loaded into the execution environment of the attached processor unit.