This chapter presents a survey of the state of the art for quality assurance for requirements. The meaning of quality in the requirements context is discussed, as is the influence of the quality assurance during requirements on other parts of the development. Different quality assurance approaches are categorized as either constructive (e.g., standards, guidelines, elicitation techniques) or analytical (e.g., inspections) and discussed with respect to their impact on the requirements quality. Based on the approaches, future challenges are discussed. The main future challenges lie in investigating the return on investment of quality assurance in the requirements context and to provide more empirical results which approach that effectively prevent or detect which problems.