Evaluating the impact of widening participation interventions can be challenging. This article discusses some of the difficulties in attributing change to complex widening participation interventions and suggests that the Theory of Change (ToC) approach can address some of these challenges by evidencing the contribution interventions have made to observed outcomes and longer-term impact. This article sets out the application of a ToC approach as a framework to plan and design the evaluation of the Academic Enrichment Programme (AEP) at the University of Birmingham, which aims to support under-represented students secure places at selective universities. The evaluation sought to explore the extent to which the programme impacted on students' academic aspirations, motivation, attainment and progression to selective universities. It presents the findings of the evaluation, which combined the ToC with a mixed methods longitudinal design spanning six cohorts of students. Qualitative and quantitative data were collected to track students' progress across their engagement with the programme and into higher education. The results suggest that the ToC programme was largely verified. The AEP seems to promote academic attainment, with AEP students outperforming national and regional benchmarks. The AEP also appears to increase entry rates to Russell Group universities for disadvantaged students, however, the effect seems to be greater when combined with alternative offers. This article demonstrates the value of the ToC approach in strengthening both the evaluation design and the contribution claims of the observed results to the widening participation intervention.
