This naturalistic inquiry evaluated the impact of early literacy intervention on children in London schools. The progress, in the 2005-06 school year, was compared for 234 of the lowest-achieving children in 42 schools serving disadvantaged urban areas. The children, aged around 6 years who received Reading Recovery in their schools, were compared with those in schools which provided them with a range of other interventions. Both groups started the year with literacy levels below that of a 5-year-old. Comparison between the groups was made for reading and writing and phonic knowledge as well as oracy, work habits, social skills, and attitudes to learning. Those children who received Reading Recovery achieved significant gains in all assessments compared with those who did not. At the end of the year the children who had received Reading Recovery had an average reading age of 6 years 7 months, in line with their chronological age. The comparison group was 14 months behind, with an average reading age of 5 years 5 months. The study also evaluated classroom literacy. A word recognition and phonic skills measure was used with all children in the sample Year 1 (age 5-6) classroom in schools with Reading Recovery (605 children) and without Reading Recovery (566 children). Children in sample classrooms, with Reading Recovery available to the lowest group, ended the year with an average reading age 4 months above that of children in comparison classrooms. (Contains 9 figures, 9 tables, and 2 footnotes.)