St. Joseph, Missouri has been designated a particulate nonattainment area. Identification of particulate sources was necessary in order to develop particulate control measures. Five techniques were used: (1) statistical analyses of historic particulate sampling data; (2) microinventories around sampling sites and evaluation with the empirical modeling technique; (3) short-term particulate sampling at additional locations; (4) chemical and microscopic evaluations of particulate samples; and (5) evaluation of major point sources. The analysis indicated that 24 to 35 percent of the particulate concentration at urban sites is generated by St. Joseph area sources as opposed to extra-regional sources. Specific sources identified by location are reentrained dust from streets, automobile emissions, industrial process and point source emissions, and exposed areas.