The Quality of Life Inventory (QOLI) is an established rating scale of self-perceived quality of life across 16 domains. Norms for different psychiatric conditions when rated via the Internet, responsiveness to change following treatment, and the clinical impact of importance-weighting items have yet to be examined. To investigate these unanswered questions, important for the continued and expanded use of the QOLI, we compiled archival screening and post-treatment data from 20 studies featuring Internet-delivered psychological interventions for seven different psychiatric conditions and an undergraduate sample, totalling over 4000 participants. Disorder-specific norms were indicated by between-group analyses and are reported here, item-by-item. The QOLI showed adequate responsiveness to change and construct validity. Discrepancies were found when conducting between-group analyses with and without weighted items (more significant differences when items were not weighted) on both the screening and post-treatment data, suggesting that weighting is a procedure that is likely to have an impact when analysing QOLI results. Limitations and the needs for future research are discussed.