This PhD thesis presents an interdisciplinary work integrating theoretical frameworks from pedagogy and psychology. It examines differences in students' academic performance in 10th grade and progression in upper secondary school. The work aims to examine the differences between boys and girls with various minority and majority backgrounds, as well as how these differences are affected by conditions in the home and school. It uses data from a school population survey in Oslo and Hedmark administered by the Norwegian Institute of Public Health (FHI). Quantitative analyses are used to examine students' school achievements and educational plans in 10th grade, as well as their progression into the 3rd year in upper secondary school. The study utilizes students' self-reports related to their perception of parenting style and social support from home and school contexts, as well as grades and educational plans. Also, registry linked data relating to ethnic and socioeconomic background are used. The results show that girls report higher grades compared to boys, across ethnic status. When controlling for socioeconomic background and experience of social support, it turns out that social support from the teacher has a strong relationship with students' grades and educational plans in 10th grade. Non-Western minority students also report lower academic performance compared to other Western and Norwegian students. Controlling for parental education reduces the differences between the ethnic groups, and parenting styles explain the differences in language performance between boys and girls across the ethnic groups. There are also differences in how parenting affects the various minority and majority students’ academic skills, as well as how they indirectly affect the relationship between students' socioeconomic background and characters. Norwegian girls also have a better progression compared to other students in upper secondary school. When controlling for prior school performance, educational expectations, socio-economic background, social support and parenting style, it appears that boys have significantly poorer progress compared to girls, across ethnic backgrounds. Students' school performance and educational expectations in 10th grade have the strongest association with students’ progress, while parents’ education and parental monitoring also affects the progression. Students’ 10th grade perceptions of social support from classmates and friends are also positively associated with their progress in upper secondary school. Non-Western girls show a robust progression in upper secondary school despite having low prior 10th grade achievement and low educated parents. It is speculated whether this may be related to parental monitorin