This paper reports some of the results of the "Raising Standards in Numeracy" project which was funded by the Welsh Assembly during 1999-2000. Schools in which pupils achieved standards significantly higher than would have been expected from their prior attainment were identified as using value-added analyses in order to explore factors and strategies that might contribute positively towards standards in mathematics. Two primary and two secondary schools were identified in each of five Welsh local education authorities (LEAs). Pedagogical factors contributing to high attainment were then explored through extended interviews with LEA advisors, head teachers, mathematics subject leaders, and classroom teachers. These factors were triangulated at classroom level through participant observation. This paper focuses on features of classroom practice, making only brief mention of factors at the level of whole school and subject leader. These features are contrasted with findings from other projects and analyzed to provide a rationale for good practice. (Contains 42 references.) (Author/ASK)