Progress is reported for a research program on the resuspension in the atmosphere of plutonium fallout deposited on the earth surface. The long-range goal of the resuspension studies is to produce a set of equations which can be used to predict the timedependent average concentration of resuspended material downwind from a source of any geometrical configuration and soil sunface characteristics. The experiments are conducted at the Nevada Test Site where plutonium-high explosive tests were performed during the period from 1954 to early 1958. The investigations have included: monitoring of soil samples for Pu; development of ultra-high volume air samplers, in-situ panticle spectrometers, particle counters, and a micrometeorology field laboratory; determination of Pu redistribution due to the rolling of soil particles pushed by winds (creep), the bouncing of wind-pushed particles (saltation), and transport by dust devils; and measurements of meteorological parameters. Results from these experiments will be used to establish a data bank on radioisotope distribution and meteorological conditions at NTS and to provide information of the relation between the source and the dose to man from existing radioactivity. (LCL)