In the processing of plied yarns, stress relaxation and recovery behavior play critical roles in determining the final characteristics and performance of the yarn. Stress relaxation refers to the phenomenon where the internal stresses within a material decrease over time when it is subjected to a constant strain. Stress relaxation affects how the yarn behaves after it has been processed. Recovery behavior refers to the ability of a material to return to its original shape or dimensions after the stress or strain is removed. Conventionally the plied yarns are produced by plying two or more single yarns after spinning but, Eli-Twist spinning incorporate twisting and plying in one single operation. Eli-Twist spinning system, patented by Sussen Elite compact spinning technology has gained considerable attention in recent times by producing two-ply compact yarns directly on ring frame, eliminating additional plying and winding operations. This book "The science of stress relaxation and recovery in plied yarns" is concerned with the stress relaxation and recovery behaviour of Eli-Twist yarn in comparison with conventional TFO yarn.