One argument for early intervention for reading difficulties is that it can sustainably improve children's reading competence trajectory (the 'inoculation model'), but there are virtually no studies on sustained effects at the end of compulsory schooling. This study reports on a 10-year follow-up of a widely used early literacy intervention, Reading Recovery. UK schools adopting Reading Recovery enrol selected teachers for a year's training, after which they provide one-to-one tutoring and typically act as literacy advisors. In a quasi-experimental, intention to treat, design, 293 6-year-olds with reading difficulties in 42 London schools were assigned to Reading Recovery (RR), standard provision in Reading Recovery schools (RRS) or standard provision in comparison schools (CS). Children were traced at ages 14 (204) and 16 (271) and data collected from the National Pupil Database. At age 14 and 16, significantly fewer RR than CS pupils were officially identified as having special educational needs, a potential consequence of reading difficulties. Using multi-level modelling and controlling for baseline reading and Free School Meal status (an indicator of poverty), at age 16 the RR group significantly outperformed the CS group on academic qualifications (GCSEs) (d = 0.52). However, the RRS group also performed significantly better than the CS group (d = 0.37), consistent with the fact that standard provision for weaker readers in RR schools differed from that provided in CS. Thus, these results support the long-term effects of early intervention but raise questions about the importance of whole-school effects and systemic intervention.