Introduction: Research confirms that young people in contact with the criminal justice system have high levels of speech, language and communication needs (SLCN). There is only one published research paper (Bryan, Freer, & Furlong, 2007) identifying the prevalence of SLCN in young people in young offender institutions (YOI) in England. There is no published research as to how speech and language therapy (SLT) services are delivered to this population. Aim: This study comprises of two main phases. Phase 1 identifies the prevalence of SLCN in young people in English YOIs and provides an updated profile of the type of SLCN these young people present with. The profiles of SLCN are analysed in association with socioeconomic background, education, mental health and offending behaviour. Phase 2 determines the purpose, structure and function of SLT services in English YOIs. Method: Phase 1 comprises of secondary data analysis of speech, language and communication assessments collected over one year at a London region YOI. Phase 2 comprises of four components; a survey followed by a semi-structured interview conducted with the lead clinician at each site, collation of six months of SLT service data from each site and six in-depth case studies provided by the clinicians working in these settings. Results: Phase 1 identified over half the participants met the criteria for a language disorder (= -1.5SD). In addition, the percentage of participants excluded from school, accessing mental health services and designated looked after child status was significantly higher than in the general population. All services involved in Phase 2 were providing one to one assessment and interventions for a range of different SLCN. Benefits could be seen in more universal service provision but resources and regime issues were seen as barriers. It was felt that the speed of change and levels of pressure were higher than in other clinical settings.