Introduction and Aims: The collection of routine outcome measurement (ROM) data provides an opportunity for service providers to conduct benchmarking to inform quality assurance practices. To conduct comparative benchmarking, it is important that services have access to comparative data. This paper aims to establish effectiveness indicators for ROM data collected within the alcohol and other drug (AOD) sector. Design and Methods: ROM data were collected by specialist non-government AOD treatment services within the Network of Alcohol and other Drugs Agencies online database (i.e. NADAbase). All participants were attending treatment within New South Wales, Australia (N = 21 572). Effectiveness indicators were calculated by using effect sizes, standard error of measurement, and rates of reliable and clinically significant change. The study focused on quality of life (EUROHIS Quality of Life Scale), psychological distress (Kessler-10) and substance dependence (Substance Dependence Scale). Results: Since 2010, 21 572 unique people have completed at least one NADAbase Client Outcome Measure. Amphetamines (36%) and alcohol (32%) were the most commonly reported primary substances of concern. Effectiveness indicators were established for the total sample, as well as for people attending residential rehabilitation (n = 8161) and community-based (n = 10 306) treatment services. Standard error of measurement was the least stringent effectiveness indicator (i.e. a higher proportion of people demonstrated improvement), while the clinically significant change was the most stringent approach. Discussion and Conclusions: The study demonstrated the utility of the NADAbase to establish effectiveness indicators for benchmarking purposes. Recommendations are provided for the use of benchmarking to inform quality assurance activities in the sector.