10% Cocamide DEA is applied directly to dry hair and is washed off with shampoo after 60 minutes. Permethrin 1% creme rinse is applied to shampooed and towel dried hair and left in situ for 10 minutes, then rinsed off with clean water. Treatments will be applied by experienced investigators throughout the study. Assessments will be made by other investigators unaware of the treatment regimen used.