As part of the continuing program to study the impact of its international assessments, the University of Cambridge International Examinations ("Cambridge") has undertaken a series of studies investigating the impact on a range of US stakeholders. This paper reports on research designed to respond to a series of washback and impact questions seeking data on: the profiles of the candidates taking Cambridge assessments and teachers preparing students for the assessments; the washback of Cambridge assessments on courses preparing students; and the impact of Cambridge assessments on the students who have taken them. Data were collected on an opportunity sample of five case study high schools and two universities. The main findings of the study are presented according to the type of data collected: questionnaires, interviews and discussions, and classroom observations. (Contains 4 tables.)