Implementing and performing early mobilization is a complex process requiring multidisciplinary input and cooperation. To gain insight in its facilitators and barriers, various surveys have been developed. A systematic review was conducted, to identify the psychometric properties, feasibility and suitability of questionnaires to assess facilitators and barriers of early mobilization in critically ill patients. Data were extracted regarding a.o. definition of early mobilization, development, psychometric properties, content and themes, question format. The search identified 537 publications of which 13 unique questionnaires were included. The questionnaires showed wide variation in extensiveness of development. Only six questionnaires actually assessed validity and reliability. Which questionnaire to choose depends on the aim of its use, required level of detail and specifics of the ICU, though three questionnaires were recommended as their definition of early mobilization covered a broad range of activities, including nursing related mobility activities. International consensus on what constitutes early mobilization is desirable.