In 1963 the National Air Sampling Network encompassed some 200 stations. This report presents the results of analyses performed on samples collected at these stations in 1963 and also results of analyses performed in 1963 on some samples collected in previous years. These results are tabulated in the Summary Table. The mean concentration of suspended particulates for 168 urban NASN stations in 1963 was 92 microg/cu. m. The mean concentration of suspended particulates for the 32 nonurban stations was 27 microg/cu. m, a level that has not fluctuated significantly in the past 6 years. Concentrations in individual nonurban samples ranged from 1 microg/cu. m to 843 microg/cu. m. Analysis of data on particulate pollutants in 100 selected cities, for the period from 1957 through 1963, shows that concentrations of most of the individual particulate pollutants analyzed are related to the concentration of total suspended particulates.