There is a lack of validated autism-specific outcome measures for large-scale evaluation of the effectiveness of psycho-educational programmes. To fill this gap the Environment Rating Scale (ERS) was adapted from an interview version to a staff-completed questionnaire version (ERS-Q). The ERS-Q was tested regarding data quality, validity, reliability and ease of understanding amongst 18 residential staff members. The ERS-Q and ERS showed comparable reliability (alpha = 0.89 and 0.93, respectively) and their correlation was 0.73. These observations support that the ERS interview can be adapted into a questionnaire without substantial loss of conceptual meaning. However, further evaluations in larger samples are needed to more firmly evaluate the measurement properties.