This thesis explores the effects of the high-stakes examination systems in Ireland and Turkey on the teaching and learning of mathematics in post-primary education. The study comprised of three parts: an exploration of teachers’ views on the high-stakes examinations in their countries, a comparison of students’ attitudes and study methods, and a classification of examination questions from recent examination papers. Questionnaires were developed for teachers and students and administered in ten Turkish and thirteen Irish schools; in addition, 48 teachers were interviewed. The qualitative data from the teachers' questionnaire was analyzed using Grounded Theory. The pupils’ questionnaire was administered to more than 1200 students and comprised of Likert-type questions organized into several scales. The quantitative data from these questionnaires was analyzed using Rasch analysis as well as other standard statistical techniques. In the third strand of this thesis, the mathematics examination questions from Ireland and Turkey were classified according to the Levels of Cognitive Demand framework (Stein and Smith, 1998). This study shows that Turkish students have significantly higher levels of confidence in their mathematical ability and are less anxious than their Irish counterparts. Students in both countries reported that when studying they try to understand mathematical ideas, they memorize formulae and procedures, and they practice examination questions. My study shows that practice is very important in Irish classrooms in particular, and Irish teachers seem to feel more pressure to teach to the test than their Turkish colleagues. However, many Turkish teachers felt that their examination system was responsible for a ‘grind school’ phenomenon. The classification of examination questions showed that most questions in Ireland and Turkey were procedural in nature; however the Turkish examinations had a higher proportion of cognitively demanding questions than the Irish examinations. The fact that the Turkish examination questions are more likely to require conceptual understanding may help to explain why Turkish teachers have a different teaching style to their Irish colleagues.