The aim of this thesis in mathematics education is to produce knowledge about problem-solving as a broad and complex phenomenon in mathematics teacher education, historically and in the present. With a multidisciplinary approach and affirmative critique, possible new understandings of the phenomenon are investigated, extended and transformed in three sub-studies and two chapters in the wrapping. The thesis builds on previous research on teacher education but seeks to contribute to a multidimensional understanding of the phenomenon of problem-solving. The first sub-study provides a configurative research review that offers a picture of the different relationships in which problem-solving is involved, and how different aspects of problem-solving are highlighted and become complementary. The second sub-study is a discourse analysis of historical texts on problem-solving where the data consists of texts written for and by teachers from the 1840s and onwards. The sub-study shows how discursive truths about problem-solving are formed and consolidated over time. The third sub-study brings attention to the materiality of problem-solving teaching, and highlights how mathematics teaching in secondary school, in the form of classroom observations, can be understood in a new materialist perspective. In addition, the thesis includes further analysis of problem-solving – presented in two chapters in the wrapping – and as a consequence the thesis may is designed as a hybrid between a compilation thesis and a monograph. In one of the chapters, previous research is traced diffractively with regard to the arguments put forward as to why problem-solving is important. In the other chapter, the results of the three sub-studies are read diffractively, through and with feminist new materialism. The thesis spans over several theoretical-methodological fields and takes the reader on a walk through the problem-solving landscape. The overall results show that problem-solving is a composed phenomenon that appears in different ways in different theoretical perspectives and methodological starting points, as well as in different times and spaces. To summarize, the thesis shows that 1) there is a need for teacher education to encourage pre-service teachers to acknowledge the multiplicity regarding both knowledge of problem-solving and the solving of problems, 2) teaching in teacher education can make visible, but also question, dualities such as thinking–acting, body–soul, rationality–emotions, woman–male in order to find other ways of understanding problem-solving, 3) when aspects of gender, inequality and other sociopolitical issues are addressed in mathematics education content in teacher education, problem-solving can be linked even more to a societal context, 4) the consideration and handling of emotions in relation to mathematics is significant as a knowledge in itself and contributes to a more composed understanding of problem-solving, and 5) new dimensions of problem-solving can emerge when the planning of mathematics teaching is based on a relational understanding of learning and supported by new materialist theory. The thesis contributes with new ways of thinking about problem-solving as a composed phenomenon, what it can entail and become, and provides suggestions for an expanded and 'respons-able' understanding of problem-solving that can contribute to further develop mathematics education in teacher education.