The importance of reading skills to academic achievement, job acquisition and future success is well documented. Most of the research on reading interventions focuses on children in primary schools but many children start secondary school with very poor reading skills and schools require evidence-based interventions to support these children. The aims of this study were (i) to explore the efficacy of a phonics-based reading intervention programme, Toe By Toe, among secondary age students with severe reading difficulties and (ii) to examine perceived barriers to implementing this intervention programme. Results showed the intervention brought about a statistically significant improvement in the students' decoding and word reading skills. Interviews with staff and students indicated a wide range of positive responses to the intervention and some key barriers to implementation. This study adds to the evidence base for the use of reading interventions in secondary schools to support students with severe reading difficulties.