A research project evaluated the low stress mechanical behavior of cotton/polyester yarns in a random fiber arrangement and in a core/sheath construction. Researchers tested each yarn and plain weave fabrics woven from each yarn in an effort to understand how yarn properties translated into fabric properties. The polyester core/cotton sheath yarn exhibited lower values for bending rigidity, bending hysteresis, compressive resilience, and tensile elongation, but higher values for compressive softness and tensile modulus. The lower tensile elongation and higher tensile modulus of the sheath/core yarn translated into a lower elongation and higher modulus for the corresponding fabric, but bending and compression properties of the core/sheath yarn were inversely proportional to the bending and compression properties of the corresponding fabric. Yarn bulk and compression properties exerted a greater influence than yarn bending properties on the bending behavior of the fabric. A closely woven, plain weave fabric woven with the less resilient and easily compressible yarns was more resilient and less compressible than its constituent yarns. 20 refs.