Foreign language proficiency can be qualitatively described at different competency levels in order to convey the meaning of the different levels of proficiency. Such proficiency levels are also used in foreign language testing in schools where empiricalquantitative methods are usually employed to establish the different levels. The present paper aims to combine qualitative and quantitative approaches with the aim of deriving valid level definitions. To achieve this aim, we discuss three typical approaches to establish levels of proficiency, i.e., the post-hoc description of arbitrarily defined levels, the definition of levels based on difficulty-determining task characteristics and model-based task construction and level definition. The latter approach will be illustrated with a description of the test development process employed in the project „Evaluation of the Educational Standards for English as a Foreign Language in Germany“. We conclude our contribution with a discussion of limitations of the three approaches and implications for teaching and research.