This study examines how working hard in school contributes to explaining gender differences in academic achievement between students of Norwegian (n = 8,002) and Pakistani (n = 862) descent in secondary schools in Oslo, Norway. Path analyses show that reported school effort explains a significant part of the gender differences in school achievement for the Pakistani sample, but not as much of the gender variation in the ethnic Norwegian sample. Working hard in school is characteristic for the Pakistani sample, especially the girls. Explanations that may account for the differences in the two samples are discussed, with particular emphasis on cultural distinctions in such areas as being native within a culture, expectations and pressure from home, social control and self-reporting.