Self-Regulated Strategy Development (SRSD) is a writing process model in which students are encouraged to plan, draft, edit, and revise their writing. In this evaluation 23 primary schools and their Year 6 teachers in the Calderdale area of West Yorkshire were randomly allocated to receive training in the SRSD approach from an external consultant. Twelve schools were allocated to the comparison group and 11 schools to the intervention group. The evaluation was set up as an efficacy trial to test the impact of using SRSD in conjunction with memorable experiences at the transition from primary to secondary school. The study was well conducted with independent randomisation and a moderate sample size. Intention-to-treat analysis was used (i.e., pupils were compared in the groups to which they were originally randomly assigned), blind marking of the test papers was undertaken, and the analysis was adjusted for school randomisation. Key conclusions include: (1) The approach had a strong positive effect on the writing outcomes of low attaining pupils at the transition from primary to secondary school among a sample of pupils in State schools in the West Yorkshire area; (2) The approach had beneficial effects for both free school meals (FSM) and non-FSM pupils; (3) These findings, in combination with existing evidence from the United States and elsewhere, suggest that the Self-Regulated Strategy Development approach has substantial promise as a literacy catch-up approach; (4) A larger effectiveness trial could be commissioned to test the approach on a larger scale and with other age groups; and (5) Teachers were trained in the SRSD approach by the North American developers, but adapted it in some ways for an English context.