Vocabulary forms the basis of all linguistic communication and is thus also of crucial importance for foreign language teaching. Interest in the topic of vocabulary is also reflected in research, where there is a growing body of research on vocabulary learning and helpful practices in vocabulary teaching and learning. In practice, it is primarily the teachers who decide in what form and to what extent vocabulary teaching and learning will find its way into the classroom. However, the basis on which teachers make their decisions in this regard remains unclear, and no research has yet been conducted on this matter for the German as a foreign language (GFL) classroom in Taiwan. The aim of this explorative-qualitative study is to reconstruct the cognitions of teachers of GFL at universities in Taiwan on the subject of vocabulary teaching and learning in order to identify the factors that have an influence on the handling of vocabulary teaching and learning beyond the individual level. With the help of semi-structured interviews and a questionnaire preceding them, insights into the individual perspectives of seven GFL teachers were collected. The methodology of the grounded theory approach was applied during data collection and data analysis. The cognitions of the interviewed teachers were first reconstructed individually and validated communicatively. Based on these results, a cross-case theoretical abstraction of the identified influences and processes that play a role in decisions concerning vocabulary teaching and learning was elaborated in the form of a concept map. The perceived degree of orientation or action competence was identified as the core category that determines the surveyed teachers' cognitions about vocabulary teaching and learning. The results of the study show that teachers' cognitions about vocabulary teaching and learning are primarily influenced by their individual learning and teaching biographies and their resulting basic vocabulary-related linguistic-didactic knowledge, as well as by the textbooks and by their perception of their learners. Obstacles and problems in vocabulary teaching and learning arise from the volume, ambiguity, and lack of systematicity of German vocabulary, from insufficient consideration of vocabulary teaching and learning in textbooks, from passivity and lack of learning motivation on the part of learners, and from insufficient linguistic and pedagogical-didactic competencies on the part of teachers themselves. Helpful practices for teachers include regular self-reflection, meticulous preparation of vocabulary teaching and learning activities, appropriate flexibility in designing the instructional situation, preliminary input, contextualization, use of electronic tools, teaching vocabulary-related learning methods, and regular administration of vocabulary tests. For the learners, extensive reading, systematization of the learning processes through category formation and contextualization, as well as trying out different learning methods and reflecting on one's own learning habits are of particular importance for successful vocabulary teaching and learning from the teachers' point of view. For an improvement of the conditions determining vocabulary teaching and learning, measures for an approximation to a target language learning environment as authentic as possible, stronger international cooperation, measures to improve the qualifications of teachers, more varied and concrete application-related forms of practice in textbooks, and a stronger role of vocabulary in language proficiency tests are recommended. This study expands the understanding of the hitherto highly neglected research field of teachers' cognitions on vocabulary teaching and learning, provides valuable insights into the mindsets of GFL teachers in higher education institutions in Taiwan, and reveals important foundations for further research and elaboration of a comprehensive theory on vocabulary teaching and learning from the perspective of GFL teachers.