Successful implementation of ultraviolet (UV) disinfection will in part be determined by the performance and reliability of UV sensor systems used by commercial UV reactors. This work reports on the findings from a UV sensor performance study conducted at drinking water UV installations throughout North America. This study was conducted as part of the AwwaRF Research Project entitled "Design and Performance Guidelines for UV Sensor Systems." The study is benchmarking the state-of-the-art on UV sensor and dose monitoring technologies through literature reviews and vendor surveys, measuring the performance UV sensor systems at North American and European UV installations, developing approaches for measuring UV sensor properties and characterizing those properties with various sensors before and after long term UV exposure, and analyzing issues with sensor properties using CFD-based UV system performance models. Results will be used to develop UV sensor guidelines with stakeholder input and developed a NIST calibration service for the UV industry. This work reports on the findings from the North American survey on UV sensor performance. Tests were conducted over the duration of the study and involved: Reference Sensor Checks - comparison of measurements made by duty and reference sensors; UV Sensor Reading vs. Ballast Power Setting - duty UV sensor measurements were made as a function of lamp ballast power setting; UV Sensor Variability - duty and reference sensor measurements using a single sensor port were recorded at minimum and maximum ballast power settings; Lamp and Sensor Port Variability - measurements using a single reference sensor mounted in each sensor port were compared; and, UVT Monitor - measurements made by UVT monitors were compared to measurements made using a bench scale spectrophotometer. Includes tables, figures.