Wireless sensors are very small computers, and understanding the timing and behavior of software written for them is crucial to ensuring that they perform correctly. This paper outlines a lightweight method for gathering behavioral and timing information from simulated executions of software written in the nesC/TinyOS environment. The resulting data is used to generate both behavioral and timing profiles of the software, using UML sequence diagrams to visualize the behavior and to present the timing information. Categories and Subject Descriptors D.2.5 [Software Engineering]: Testing and Debugging Keywords Wireless Sensor Networks, Software Monitoring