<p>Individuals who can solve the problems in everyday and business life is one of the primary goals of education due to the necessity to have problem solving skills to cope with life problems. Problem solving has an important role in mathematics education. Because of that, this research is aimed to examine the differentiation of secondary school students’ problem solving success according to gender, class level, and mathematics course grade. Moreover, this paper explores the effect of secondary school students’ attitudes toward mathematics and problem solving on problem solving success. The participants were 77 fifth-graders and 81 sixth-graders who were studying in three different secondary schools in a large city in Turkey. Two different attitude instruments and a problem solving test were administered to these volunteer fifth- and sixth-graders accompanied by mathematics teachers. Additionally, the students’ mathematics course grades for the fall semester were obtained and used in the research. The results revealed that sixth-graders were more successful in problem solving than fifth- graders. The problem solving success of female and male students was similar, and there was an intermediate positive relationship between problem solving success and course grade point averages. The students’ attitudes affected their problem solving success.</p>