Requirements traceability provides support for many software engineering activities like impact analysis, requirements validation and regression testing. In addition requirements traceability is the recognized component of many software process improvement initiatives. Requirements traceability also helps to control and manage evolution of a software system. This book presents a systematic review and a framework for requirements traceability. The systematic review is aimed at presenting fair evaluation of research concerning requirements traceability over the period 1997 – 2007. Moreover, two companies have been interviewed to understand the practice of requirements traceability in industry. Based on the analysis of systematic review results and industrial interviews, this book presents a framework for requirements traceability called ‘Three Level Framework for Requirements Traceability (TLFRT)''. This framework has been statically validated in two companies. The validation of TLFRT in industry resulted in compilation of lessons learned, which ensures that this theoretical framework could also be used in real industrial environment.