Teens and Toddlers is the only youth development programme in the UK designed to raise the aspirations of young people by pairing them as a mentor and role model to a child in a nursery who is in need of extra support. This transformative work experience, combined with classroom training, teaches young people interpersonal skills and builds their sense of responsibility in order to enable them to make positive decisions about their education, their health and their future. We undertook research in order to investigate the extent to which the programme has an effect on children attending those nurseries in relation to their sociocognitive development. To date, an evaluation of this kind had not been undertaken for the Teens and Toddlers programme. With the attainment gap ever increasing, the research objective was to evaluate the effect of weekly mentoring from "Teens and Toddlers" participants on pre-school children can positively impact on pre-school children's development. Method: The effects of the intervention were measured using the seven areas from the Foundation Stage Early Learning Goals: Personal, Social and emotional development skills; Communication, and language, Literacy, Mathematics, Understanding the world, Expressive art and design and Physical development. Assessments were made by nursery teachers at the beginning and at the end of the programme. Controls (n = 75) were selected and matched with the experimental group (n = 85) on the basis of age, ethnicity, ability and gender. Results: The results show that the experimental group show significantly greater improvement in Communication and language (F(1,162) = 39.3, p 0.01), Physical development (F(1,162) = 7.0, p 0.05), Understanding the world (F(1,158) = 5.03, p 0.05), Expression and design (F(1,158) = 4.8, p 0.05) compared to the controls. There were no significant differences between the control group and experimental group for Personal, social and emotional development (F(1,162) = 4.8, p = .40), Literacy (F(1,159) = 2.0, p = .153) or Mathematics (F(1,160) = 5.0, p = .43). Conclusion: Findings suggest that the experiences children gain from this intervention can be beneficial in relation to their sociocognitive development. Evidently, interventions like Teens and Toddlers may help in providing the best opportunity for a smooth and successful transition into school and their future. Findings are discussed in relation to potential limitations of the study. (author abstract)