Due to the pressure to economize, increased consumerism and concerns about quality in relation to costs, the assessment of the outcome of assistive technology (AT) has been given increasing attention in recent years. The political and economical call for rationalising the amount of recourses spent on assistive technology, but also the intention to enhance the outcome of AT, make insight into the outcome of provided assistive technology necessary. The instruments and methods involved in the assessment of outcome are the topic of this special issue. The prime objective of this special issue is to present a set of instruments that can be used to study the effects or costs of AT delivery. Through the provided standardised description the reader is enabled to judge the applicability to specific conditions and the soundness of each instrument in general. Because the discipline of AT outcome assessment is relatively young, only few instruments specifically designed to measure outcomes of AT and with demonstrated soundness are available, and the applicability of outcome instruments from adjacent fields of application is to be demonstrated anew. However, the application of a well developed instrument does not automatically guarantee appropriate assessment of AT outcomes. An instrument may not be suitable for a specific type of AT and its use, or the circumstances of application may vary considerably from those during its development,due to cultural and/or language variation. The set of instruments included in this issue covers most of the best ones presently available and should be considered for use when appropriate. A second objective of this special issue is to stimulate the use of standardised instruments. To facilitate comparisons of outcomes of AT, either between users, AT alternatives or use conditions, the data to compare should preferably be obtained with the same instruments. Moreover, the application of standardized instruments may support the effect of AT use because a better informed selection can be made on the basis of the outcome assessment. Finally, a special issue providing an overview of the state of the art may serve as an inspiration for further development of existing or new instruments as it outlines topics requiring further attention.