Though there are several studies reported on sewing tension, thread and seams characteristics, still there is a lack of information and knowledge regarding - the role of various factors especially the behaviour of different types/structures of threads affecting tension peak built up during a sewing cycle; on the effect of different thread structures on the strength loss of sewn thread; causes for the difference in the loop and knot strengths compared to simple tensile strength for various thread structures; on the influence of thread and fabric properties, thread structures and certain sewing parameters on seam strength, seam security and puckering. This book attempts to fill the knowledge gaps comprehensively so as to help the sewing community to effectively utilise sewing threads to get the best possible end products produced by their manufacturing processes.