Considering that valid and reliable assessment is an indispensable prerequisite for adequately designing financial education, we describe the development and validation of a new test instrument for measuring a central facet of financial literacy. Our research activities are based on a competence- oriented view of financial literacy, defined as the potential that enables a person to effectively plan, execute and control financial decisions. Moreover, we adopt a situational judgment approach, which is mostly used in the context of personal psychology. On this basis, we developed a test instrument with 11 situations and 46 items, representing three individual cognitive facets of financial literacy (evaluation of own revenues, planning expenses in agreement with own needs and possibilities/income and drawing up a budget). To validate the instrument, we then conducted an empirical study with 206 young adults. This study yielded good results regarding the test dimensionality and validity of the scales and fairly acceptable findings for item difficulty, item total correlation and reliability. As with other situational judgment tests, this latter result may have been caused by problems of social desirability, among other things. Thus, further studies and the reformulation of items are necessary.