The Crime and Disorder Act (1998) requires all local authorities (LAs) to have a multi-agency team whose role is to support children and young people (CYP) known to the youth justice system. This thesis examines the current and potential role of educational psychologists (EPs) in working with youth justice services to promote better outcomes for those CYP. The first paper describes a systematic literature review (SLR) exploring the general role and function of EPs in working with youth justice services. The second is an empirical study, employing a survey method of semi-structured interviews, carried out across two LA youth justice services to explore their role in eliciting and integrating the views of CYP and their families, and how EPs may contribute. The SLR identified 15 possible functions of the EP role when working alongside youth justice services. Furthermore, these functions exemplified how EPs are working as scientist-practitioners within complex, real-world contexts. Findings from the empirical study suggest that there are challenges to inter-disciplinary work between the youth justice service and the educational psychology service, with one key challenge pertaining to youth justice workers (YJWs) not always being fully aware of the breadth of the EP role. Ways of working together were also identified and showed that there is scope for EPs to support YJWs to meet individual needs of those with special educational needs and disability (SEND), and to develop knowledge and understanding of psychological frameworks which would support YJWs in eliciting views and in other aspects of their work. The research considers links to theory and practice and identifies how EPs can work as scientist-practitioners within the youth justice context. Implications for future research are considered, particularly with consideration to raising awareness of the role the EP. To increase the impact of the research, a dissemination strategy for sharing with the research sites and to the wider EP community is considered.