As a result of extensive immigration, consisting largely of refugees, Sweden has undergone a fast demographic change during the last 25 years. In 2016, approximately 17% of Sweden’s inhabitants were born outside of the country. Sweden was the country in the European Union granting most refugees asylum in proportion to its population, and the EU country that had most asylum-seeking unaccompanied minors, in absolute numbers. The Swedish education system has had obvious difficulties to cope with the situation, inter alia reflected in considerable gaps in non-immigrant versus immigrant student achievement results and completion rates, which are above average when compared to other Western nations. This chapter provides a brief overview of the cultural composition of the student population within Sweden, including its evolution over time. The trajectory of achievement results on national and international large-scale assessment measures are examined in relation to non-immigrant and immigrant student groups. The authors discuss the range of policy approaches at national and local levels that have been adopted in Sweden to close these achievement gaps and reduce the levels of school dropout and non-completion.