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 two-fold (i) to explore the efficacy of a phonics-based reading intervention programme, Toe By Toe, among a group of 30 secondary age students with severe reading difficulties from 2 large schools in the London borough of Barking and Dagenham; and (ii) to examine perceived key barriers to implementing this intervention programme in secondary schools with a view to better understanding how these barriers could be overcome in practice. A quasi-experimental mixed methods design was used to evaluate the efficacy of Toe By Toe: 15 students allocated to an Experimental group and 15 allocated to a Waiting Control Group (matched at baseline for single word reading accuracy). Quantitative semi-structured interviews were also carried out ascertain the views of the students and teaching staff on the intervention programme and its implementation. Results showed the intervention brought about a statistically significant improvement in the student's phonic decoding accuracy, single word reading accuracy and phonic decoding fluency skills. The intervention did not improve sight word reading fluency, passage reading fluency or comprehension. Interviews with staff and students indicated a wide range of positive responses to the intervention and some key barriers to implementation including cost and logistics. In conclusion, the intervention can be used with secondary-age English-speaking students to raise their reading skills in the areas indicated but care should be taken that users are aware of its limitations and potential barriers to implementation. Educational Psychologists can support schools in implementing an intervention of this nature. This study adds to the evidence base for the use of reading interventions in secondary schools to support students with severe reading difficulties.