As wireless sensors networks become a critical part of applications with significant scientific, economic, and safety impact, issues of system and data integrity have gained importance. Careful design and calibration prior to deployment are insufficient to ensure integrity in the presence of environmental uncertainties, hardware and software faults, changes in hardware characteristics, and malicious manipulation of system behavior. The fragile nature of current systems is a bottleneck in scaling the embedded sensing technology. This poster describes CENS research in three different aspects of the integrity problem: sensor data integrity, software faults, and security attacks.