Mathematics, by its very nature, is a science based on metacognitive skills. Nowadays, pure meaningless knowledge is described as easy to attain but useless unless you know how to use it. Since being able to make knowledge relevant, use it and find solutions to problems is valuable today, problem solving and problem posing are paramount skills. This book entitled "Solving and Posing Mathematical Problems - Problem Solving Strategies and Mathematical Problem Posing Competence" aims to present qualitative research work. It was carried out with eight students in their first year of high school, on the factors affecting their mathematical problem-solving and problem-posing skills. The results of this study have important implications for the teaching of problem solving and problem posing in mathematics, and can help teachers to better support their students in developing their skills in this area.