The UV-B Monitoring and Research Program (UVMRP) is continually interested in offering the highest achievable data quality to the public via its web site. Over the history of its operation, UVMRP has been an advocate and an investor in periodic efforts to compare its data with other national and international measurement programs. The history of the intercomparison activity, in which UVMRP became a participant in 1996, generally paralleled the concern of the international community over stratospheric ozone depletion and the need to monitor as closely as possible the downwelling UV-B radiation. UVMRP activity in addressing data quality concerns commenced with participation in the third North American Interagency Intercomparison of Ultraviolet Monitoring Spectroradiometers as detailed in Early et al., (1998). Then again in 1997 the fourth intercomparison was held at NOAA's Table Mountain Facility near Boulder, CO that was sponsored by NOAA1, ASRC2, EPA3, NIST4, NSF5, SERC6, USDA7 and YES8; see Lantz et al., (2002), for a detailed account of this intercomparison. The most recent of this series of intercomparison activity took place, again at the Table Mountain Test Facility, in 2002 and has been documented in Lantz et al., (accepted for publication in Journal of Applied Remote Sensing, 2008). It was during the 2002 intercomparison that the red light leakage problem was suggested as an explanation of discrepancies between UVMRP UV-MFRSR measurements compared with other filter instruments, and this realization initiated an adjustment to the instruments lamp calibration factors supplied by NOAA's Central Ultraviolet Calibration Facility. The most recent intercomparison in which UVMRP participated took place in May, 2005 at the Norwegian Radiation Protection Authority (NRPA) site at Osteras, Norway about 10 km north-west of Oslo. UVMRP supplied YES8 UV-MFRSRs for intercomparison with filter instruments from NILU-UV9 and GUV9 instruments. Several agencies also deployed spectroradiometers and all participants calculated a UV Index as the standard signal for intercomparison. For a detailed account of this activity please see Johnsen et al., (2005, 2007).