In April 2021 the Behaviour Hubs programme was launched as a three-year programme to support schools and Multi-Academy Trusts (MATs) in improving behaviour culture and practice. Funded by the Department for Education (DfE), this programme facilitates close collaboration between 'lead' schools, known for exemplary behaviour cultures, and 'partner' schools striving for improvement. The primary goals are to a) ensure teachers feel supported by senior leaders in managing misbehaviour and consistently applying behaviour policies; b) design and implement effective behaviour systems, creating or strengthening overall school behaviour culture; and c) promote and disseminate best practices in behaviour management. Over 650 schools have received direct, in-person, peer-to-peer support, while more than 400 schools have gained access to support via the bespoke MAT pathway. In 2023 NatCen was commissioned by the DfE to continue the evaluation of this programme; building on the partially completed evaluation by Ecorys which included design of an initial Theory of Change and qualitative and quantitative data collection. The evaluation aims to: (1) determine whether the programme has met its strategic objectives and achieved its projected outcomes for schools, staff, and pupils; (2) understand how and why the intervention has (or has not) met its objectives, by developing and testing the programme's Theory of Change (ToC); and (3) investigate the change mechanisms triggered by the programme that have produced the observed outcomes and impacts, examining variation across different schools and respondent groups. This interim evaluation report presents the findings obtained to date.