Objective: The study aimed to design and evaluate a health behaviour change intervention for looked after young people, targeting sexual health, smoking, exercise, healthy eating and non-dependent alcohol and drug use. Design: A pre-post intervention evaluation was undertaken exploring health behaviours and wellbeing. Methodology: The one-to-one intervention was individually tailored to each person. Young people eligible for the intervention were aged 11 years and over and were "looked after", meaning they were under a supervision order with a local authority in Scotland, or were a care leaver. A total of 144 young people referred to the intervention service between March 2009 and January 2014 were eligible for the evaluation. Evaluation data were analysed using standard statistical tests on SPSS. Results: Behaviour change techniques, including goal setting, action planning, barrier identification/problem solving and motivational interviewing contributed to improvements in all areas. Difficulties with consent and follow-up were highlighted as barriers to effective evaluation. Conclusion: Improving the current health of looked after young people with a view to prevent future ill health using a tailored intervention with behaviour change techniques enables this group to improve health behaviours, despite numerous challenges in working with these vulnerable clients.