Professional consensus panels have strongly recommended Intensive Behavioural Intervention (IBI) as the treatment of choice for young children with autism. Researchers have linked treatment quantity to better results; however, few attempts have been made to link other treatment factors (i.e., quality) to outcome. This study presents information about the reliability and validity of a pilot version of a measure to evaluate the quality of IBI (the York Measure of Quality of Intensive Behavioural Intervention or YMQI). Inter-rater reliability and internal consistency were generally adequate, although some items and categories were weak. Similarly, criterion related validity and construct validity were adequate for total scores and most categories when a subjective approach to coding was used. Although results were promising, future research is needed before the YMQI can be used as a reliable and valid measure or treatment quality. Research implications and directions for future research are discussed.