A process-time diagram showing the execution history of individual processes and the interactions between processes can be a very useful tool in understanding the behavior of a distributed or concurrent application. Managing the size of these visualizations via suitable abstraction facilities is essential for longrunning and complex applications. This paper describes Poet, a tool that collects and visualizes event traces from applications running in several different target environments, such as OSF DCE, ABC++, SR, and PVM. To manage the complexity of the resulting visualizations for non-trivial executions, Poet supports abstraction facilities in both the process and time dimensions. These abstraction facilities enable Poet to visualize distributed executions on a number of abstraction levels. To achieve target-system independence, Poet makes as few assumptions as possible about characteristics that must be possessed by all target environments. Information describing each target environment is placed in configuration files, allowing a single set of Poet executables to be used for all target environments.