Evaluation is now a mainstream activity in American society. The demand for evaluation far exceeds the supply of professional evaluators who are highly trained and hold membership and regularly attend the American Evaluation Association (AEA) and/or other comparable regional or national Voluntary Organisations for Professional Evaluation (VOPEs). The professional evaluators in the AEA belong to 30 regional local affiliates and/or participate in over 60 topical interest groups (TIGs), including government evaluation, advocacy and policy change, business, leadership, and performance, community development, and democracy and governance. This chapter describes professional evaluation in the U.S., including institutionalising evaluation, current trends in the federal evaluation market, evaluation policy, guidelines for practice, professionalisation, university-based programmes, and evaluation standards. Implications and future directions for professional evaluators in the U.S. are discussed.