In this paper, we explore the results of a short-term concept-based pedagogical intervention on the learning of declension as a meaning-making resource among US university learners of German. The pedagogical approached derived its principles from Vygotskian sociocultural psychology, namely the role of explicit, scientific (i.e., abstract and holistic) concepts in promoting development. The pedagogical approach centered on the teaching of the concept of focus, which was supported with lessons on word movement and its functions in German in comparison to English, as well as the role of morphology (i.e., declension) in assigning roles to determiner phrases in German. Results show that students made significant gains in their ability to interpret the roles of determiner phrases in German sentences by attending to morphology, and they began to attempt to mark determiner phrases at a significantly higher rate following the intervention in a writing task. We discuss the results in relation to pedagogical and theoretical implications, and we offer several avenues for future research.