In February 2009, the Higher Education Funding Council for England (HEFCE) commissioned RAND Europe to review approaches to evaluating the impact of research as part of their wider work programme to develop new arrangements for the assessment and funding of research--referred to as the Research Excellence Framework (REF). The objectives were 1) to review international practice in assessing research impact and 2) to identify relevant challenges, lessons and observations from international practice that help HEFCE develop a framework for assessing research impact. The report presents the findings of the authors' review, based on four case study examples of impact evaluation approaches: the Australian Research Quality and Accessibility Framework (RQF), the UK RAND/ARC Impact Scoring System (RAISS) method, the US Program Assessment Rating Tool (PART) framework and the Dutch Evaluating Research in Context (ERiC) framework. Two appendices are included: (1) Long List of Frameworks; and (2) References. (Contains 1 table and 6 footnotes.) [This report was prepared for the Higher Education Funding Council for England.]