Students from seven schools, some from English-speaking (N=226) and some from non-English speaking (N=60) families, were tested for reading achievement in grades 1, 2, 3 and 6, and for mathematics achievement in grade 6. Students from non-English speaking families achieved significantly poorer reading results than those from English speaking families, and these differences were consistent and stable across grades 1-6. Longitudinal analyses suggested that the effect occurred primarily in grade 1 and that the lower reading achievement scores obtained by students from non-English speaking families in subsequent school years could be explained by the poor reading performance in grade 1 without taking into account the home language. The group differences were quite specific to language and reading skills and did not generalize to performance in mathematics. In year 6 the two groups did not differ in mathematics measures and students from non-English speaking families scored significantly better after controlling for language skills. Students in the two groups differed on many variables (for example, socio-economic status and home environment) so that causal conclusions are not justified. However, the specificity of the group achievement differences to language and reading skills suggests that home language may be an important determinant of early reading, and that early reading is in turn the primary determinant of subsequent reading performance. (Author)