Conventional metaphors are a fundamental component of everyday communication, yet they are often overlooked in post-secondary German-language programs. This study examines the extent to which vocabulary breadth influences 19 L2 German learners' comprehension of conventional German metaphors, particularly those that exhibit cross-linguistic differences in lexical form and conceptual motivation. Employing a mixed-methods analysis, this research investigates the interpretations of 40 highly-frequent, polysemic verbs in metaphorical contexts by L2 German speakers. The findings indicate a significant relationship between the breadth of a learner's vocabulary and their ability to accurately decode conventional metaphors. However, the study also reveals that learners with extensive vocabularies may be misled by their own knowledge, frequently failing to recognize extended metaphorical meanings despite familiarity with the lexeme and confidence in their interpretations. These results highlight the intricate interplay between lexical knowledge and cross-linguistic differences in figurative language, underscoring the necessity for nuanced instruction in metaphor comprehension.