Objectives: Europe has many health technology assessment (HTA) agencies, each producing their own HTA reports. Adapting HTA reports for different contexts could reduce the need for multiple reports on the same health technology with resultant saving of time and resources. This study aims to examine and understand the process of adaptation, and to develop a toolkit that would help the adaptation of reports produced by other countries. Methods: The methods used were a review of the literature; a survey of twenty-nine European HTA organizations, two rounds of a Delphi survey, a face-to-face meeting of twenty-one European network for Health Technology Assessment (EUnetHTA) representatives, iterative rounds of review, and two rounds of quality assurance testing (termed applicability testing). Results: Descriptions of previous examples of adaptation in the literature are sparse. Most respondents had previous experience in adapting reports, and all believed that adaptation was useful, and there was the ability to benefit from the use of a toolkit to aid in the process. EUnetHTA Partners developed and tested an adaptation toolkit. The toolkit is composed of a series of checklists and resources that identify or clarify the relevance, reliability, and transferability of data and information from existing reports. Conclusions: Consensus of opinion from twenty-nine European organizations/networks has indicated that the adaptation of HTA reports would be desirable and beneficial. A This study was undertaken within the framework of the European network for Health Technology Assessment (EUnetHTA) project, which was supported by a grant from the European Commission (Grant agreement 2005110 project 790621). This work, although coordinated from NCCHTA in England, was very much a collaborative effort between twenty-nine groups across Europe. Further details and all other acknowledgements can be found in: Kristensen et al. (15). The role of NCCHTA in the EUnetHTA project was jointly funded by the NIHR Health Technology Assessment Programme (project number 05/52/01). The sole responsibility for the content of this publication lies with the authors. The European Commission and the Department of Health in England are not responsible for any use that may be made of the information contained therein.