An experiment evaluated the influence of Dyneema content on the air permeability, water vapor transmission, and thermal energy dissipation of cotton/dyneema fabrics. An increase in Dyneema content increased yarn and fabric strength. Core wrap yarns exhibited lower strength, elongation, ad air permeability in the wet state than did random blend yarns. Dyneema composition influenced both dry and wet air permeabilites of the fabric. Cotton fabrics were the least resistant to water vapor diffusion. Water vapor diffusion resistance exhibited an inverse relationship with air permeability in both dry and wet states. Dyneema content did not affect the amount of heat energy dissipated through the fabric. 6 refs.