The Foreign Language Learning (FLL) programme aimed to improve the English language attainment of Year 3 and 4 pupils through a detailed curriculum of weekly French classes with linked activity in English lessons. The programme, created by the Education Development Trust (formerly CfBT), lasted for three half-terms. French classes were 45 minutes long and the linked activity required an additional 15 to 30 minutes of English class time per week. Teachers were provided with detailed lesson plans and three days of training in delivering the curriculum. The project was a randomised controlled trial. 46 schools participated, mainly from Greater London, the South East, and the North East of England. 169 individual classes in the 46 schools were randomised to receive either FLL or business as usual. The process evaluation involved observations of the teacher training, observations of the lessons, and interviews with teachers. The trial took place between January 2014 and March 2015. The project specifically evaluated the impact of the particular FLL curriculum with its linked English literacy activity. Some children in the control group also did foreign language lessons, but without the FLL curriculum and the linked English activity. Key Conclusions included: (1) Children in FLL classes made no additional progress in English language compared to children in other classes in the trial. The 1 padlock security rating means we have very low confidence that there was no difference and that this was due to FLL and not affected by other factors; (2) Children in FLL classes who had ever been eligible for free school meals made 2 months' fewer progress compared to other ever-eligible children. However, we have very low confidence that this result was not affected by other factors; and (3) There was a lot of variation in how the intervention was implemented. Not all teachers delivered the linked English literacy activity and some schools delivered fewer weeks of FLL than prescribed because of staffing or timetabling issues. This study investigated whether teaching Year 3 and 4 primary school children for one hour a week using an 18-week curriculum of French language and linked English literacy would have an impact on their English language attainment (as measured through testing of grammar, punctuation, and vocabulary). This randomised controlled trial found no evidence of such an effect. Additionally, no effect was found for: boys, girls, children who had ever been eligible for FSM, children with English as their main language, or children with another language as their first language.The results of this evaluation differ from those of two large-scale retrospective cohort studies with matched intervention and control groups that showed an impact of foreign language learning on English language attainment in the United States (Rafferty, 1986; Taylor-Ward and LaFayette, 2010). This variation may be a result of the shorter length and reduced intensity of this intervention compared to those studied in the US (18 weeks/60 minutes per week vs. one to three years/minimum 150 minutes per week). Additionally, this evaluation tested a particular type of foreign language teaching (which was combined with some linked English literacy activities) against a control group where there was often some foreign language teaching being undertaken. This type of comparison was different from those US studies where the control group had no such foreign language teaching. [Dr John Jerrim assisted with the evaluation design and the randomisation of classes.]