Among 7 soils from various parts of the United States, chlorinated hydrocarbon insecticide emulsions penetrated least in arid soils from Arizona and Oregon and most in soil from Missouri. Soil moisture at application time appeared to enhance penetration. After 24 hours in most tests, more than half of the insecticide applied was found in the upper ¾ inch of soil. The parts per million of insecticide measured in 6 layers of soils did not differ appreciably in samples taken 1,4, and 24 hours after application. Chlordane, dieldrin, and heptachlor were the insecticides tested.