The imbalance in the labor market between the supply of and demand for skills is a widespread phenomenon that may contribute to unemployment and lower productivity and competitiveness. This diploma thesis aims to explore and understand the complex phenomena of skill mismatches on the labor market. As skill mismatch manifests itself in various forms, there exist different but also related concepts of educational or qualification and skill mismatches. In the first part a clear distinction between skill and qualification mismatch is made, the links between different types of mismatches are described and the debate of using each of the concepts is situated as well as the comparison of advantages and disadvantages of different concepts. Next part of this thesis concerns also with potential causes of mismatches in the labor market as well as its consequences and implications for individuals, businesses and society as a whole. In the next section, the information on possible measures of educational or qualification and skill mismatches is offered and the comparison of these measures is made. A new approach for measuring skill mismatch is introduced. Due to published results from PIAAC survey, which contains measures of skill proficiency and also information about qualifications, educational as well as...