This thesis consists of four empirical essays on the economics of education. The first two essays discuss topics from vocational education and training and focus on firm behavior. The first essay analyzes the effect of the German Labor market reform on the training behavior of German firms using Switzerland as a counterfactual. The second essay identifies the effect of a public procurement policy in favor of training firms on firms’ willingness to train. The third Essay analyzes the effects of the labor market environment on the costs to fill a vacancy. Training is also a recruitment device for firms, and thus, hiring costs are important opportunity costs of training. Therefore, hiring costs also affect a firm’s training decision in dual apprenticeship systems. The fourth Essay examines the introduction of a “numerus clausus” in Swiss medical schools and analyzes whether the implementation of an aptitude test reduces University dropout.