Butterfly Phonics aims to improve the reading of struggling pupils through phonics instruction and a formal teaching style where pupils sit at desks in rows facing the teacher. It is based on a course book created by Irina Tyk, and was delivered in this evaluation by Real Action, a charity based in London. Real Action staff recruited and trained practitioners to deliver the intervention. These practitioners worked with trained teaching assistants to teach classes of six to eight pupils, although some groups were larger. Pupils were eligible for participation in the trial if they did not reach level 4 in their Key Stage 2 SATs or their reading skills were at least a year behind their chronological age. The evaluation was set up as a randomised controlled trial, which compared the progress of pupils who received Butterfly Phonics to a "business-as-usual" control group. Key conclusions include: (1) This evaluation provided evidence of promise; there was a positive, statistically significant effect on the primary outcome measure of reading comprehension. However, this effect size was lower than the minimum detectable effect size of the trial, so we cannot confidently conclude that the effect was due to the intervention and did not occur by chance; (2) The secondary outcome measures indicated positive impacts on children's literacy skills, but these were not statistically significant; (3) This intervention is recommended to take place during the school day, when it is easier to secure sustained co-operation and support from school staff. Where that support was present, the intervention was able to progress more satisfactorily than in schools where it was lacking; (4) Schools should ensure that people delivering the intervention receive training in the Butterfly method so that it is implemented as intended; and (5) Further research could investigate the intervention's impact on early readers. Its emphasis on larger word units and comprehension skills might enable a more rapid progression in early reading than a pure phonics course. [The project was independently evaluated by a team from the Centre for Evaluation and Monitoring (CEM) and the Wolfson Institute for Health and Wellbeing at Durham University.]