Analyzing the performance of multi-threaded applications. An analysis and visualization of thread executions is performed on a graphical timeline using samples of thread execution. This allows users to understand when their application threads are executing, what they were executing, the degree of concurrency in thread execution, and the order in which work is performed in their application. The visualizations and analysis also allow users to sample thread execution contexts using a graphical user interface, as well as the generation of execution profile reports that may be filtered for a specific time range of execution and a subset of the threads running in the application.