The purpose of this dissertation is to assess current levels of financial literacy among ninth-grade high school students in the Netherlands in order to identify which groups are particularly vulnerable to financial illiteracy. Once these baselines are established, the objective will be to systematically design, develop, and evaluate a financial education program to improve financial literacy among high school students in the pre-vocational track (VMBO) in the Netherlands. This dissertation consists of five studies. In the first study, we provide evidence of the effectiveness of existing financial education programs for children and adolescents and describe the key characteristics of the pedagogical design of successful programs. The second and third study describe the exploration of the financial literacy levels of high-school students, the factors that influence these levels, and an investigation of the relationships between the four different components of financial literacy in order to know the aspects of financial literacy that most influence financial decision-making among adolescents. The outcomes of the first, second and third study are used to systematically design, develop, and qualitatively evaluate a financial education program (study 4). In the last study, the effects of the financial education program on high school students’ financial literacy are examined. It is hoped that the insights gained will inform educational practice and policymakers in implementing and teaching financial literacy in schools, as well as shed light on the potential for further research.