No gender differences in problem solving (PS) performance were observed in Switzerland, like in many other countries. This might seem astonishing, given the strong relation between PS and, to a smaller extent, reading, two domains where a relevant gender gap exists. With regard to Swiss specific features, we are interested in finding out whether gender differences appear also in PS after analysing the results by level of the problem solving scale. Moreover, although there is no gender gap on the national level, three Swiss cantons do show a significant difference in problem solving competency between boys and girls. Does this discrepancy depend on the system factors that characterize the diverse cantonal education systems? As a last issue, we would like to learn if there is a stronger relationship between ability in PS and a particular content area of mathematics, where boys and girl may perform differently. The gained information could enable policy makers to individuate groups of students, for which intervention is more necessary.