This status report documents the effort by the National Exposure Research Laboratory (NERL), Office of Research and Development (ORD) of the U.S. Environmental Protection Agency (U.S. EPA) to provide methods of measurement, including calibration procedures that meet the requirements for diagnostic testing of models describing atmospheric photochemistry. These requirements include a measurement uncertainty of plus or minus 0.2 ppbv (plus or minus 0.1 for NO2) at 1.0 ppvb (or equivalent for particles) for compounds mentioned here as specified by scientists in the AMD, NERL. New developments for monitors of NO2, HCHO, H2O2, HNO3, HONO, NH3, VOCS (including n-aldehydes), particulate nitrate, particulate sulfate, and particulate ammonium are discussed in the report. Descriptions of instrument design and measurement principle for NO2, HCHO, and water soluble gases and particulate matter are presented. Results from the 2002 Tampa, PA BRACE study, the 2001 Philadelphia, PA NE-O3PS study, and the 1999 Nashville, TN SOS field study are also shown. Of particular note are the preliminary results of field monitoring of NO2 in the BRACE field study with systems using new commercial photolytic converters for NO2 to NO conversion followed by chemiluminescence's detection.