The demand for alcohol and other drug (AOD) treatment in Australia greatly outweighs the resources available resources, with services only meeting half (56%) of the demand in Australia. As a result, current healthcare models prioritise the volume of AOD service delivery (number of clients seen) over quality. Although the ideal AOD treatment episode is 6-12 sessions, clients typically only attend 1-2 sessions. The first treatment session is primarily used for an assessment of the client's substance use, mental health and other related factors, meaning very few clients receive any evidence-based treatment, resulting in poor outcomes and high rates of relapse. A radical shift in AOD practice and policy is needed to increase access to evidence-based, high-quality care. A stepped wedge cluster randomised control trial of people enrolling in outpatient drug and alcohol treatment across two states in Australia. First Step, was positioned at the beginning of AOD treatment to provide a low-intensity brief intervention to all clients initially (across 2 sessions), followed by delivery of more intensive treatment (if required), consistent with a stepped care approach. Clients completed outcome measures to provide assessment information before service entry, enabling treatment to commence immediately in session one. The trial included 8,270 clients enrolling in services from August 2022 to April 2024. This abstract includes initial findings related to changes in treatment engagement. Final results will be reported at the congress. There was an increase in the number of clients receiving any treatment from 48% in the pre-implementation phase to 71% in the post-implementation. In the post implementation phase, 33% of clients attended two sessions, compared to 21% in the pre-implementation phase. Positioning a brief intervention at the beginning of treatment, with clients completing outcome measures before enrolment, enabled treatment to begin in the first session and improved treatment engagement among clients.