Success for All (SfA) is a whole-school approach to improving literacy in primary schools. Teachers receive training in areas including group learning strategies, phonics, and assessment, and are provided with structured daily lesson plans and teaching materials. There is also support for school leadership in areas such as data management, ability grouping, and parental engagement. In this trial, the programme was delivered over two academic years on a whole-school basis by teachers and classroom assistants who were trained and supported by the Success for All Foundation. In total, schools received 16 days of training and support. Although the intervention was delivered on a wholeschool basis, the evaluation focused only on the outcomes of 1,767 pupils starting in Reception class, following them through until the end of Year 1. Fifty-four schools took part in this effectiveness trial. An implementation and process evaluation ran alongside the trial to explore implementation and delivery challenges. The evaluation took place between September 2013 and June 2016. Key conclusions include: (1) Children who took part in Success for All (SfA) made 1 additional month's progress, on average, after two years compared to children in other schools. The 3 padlock security rating means that we are moderately confident that this difference was due to SfA; (2) Children eligible for free school meals (FSM) made 2 additional months' progress after two years, compared to FSM children in control schools. The smaller number of FSM pupils in the trial limits the security of this result, though combined with other findings in the report it provides some evidence that SfA does improve literacy ability for children eligible for free school meals; (3) Of the 27 schools receiving SfA, 7 dropped out of the programme completely, and 5 did not implement it to the minimum expected level. There is some indication that lack of engagement with the programme resulted in poorer implementation which may have affected the programme's impact; (4) Some schools found SfA prescriptive and adapted the content and delivery of the programme. However, there is some evidence that schools delivering SfA as prescribed by the developers saw larger gains in children's literacy after two years than those that completed fewer aspects of the programme; and (5) Overall, schools that successfully delivered SfA were enthusiastic and valued the programme in their school.