This chapter explores the pedagogical potential of metaphorical discourse in English for Specific Purposes (ESP), focusing on its application in an Environmental Science ESP course at a Romanian university. Grounded in Conceptual Metaphor Theory, the study investigates how metaphor functions as both a cognitive and communicative tool that enhances student engagement, comprehension, and academic performance. Drawing on a 14-week case study comparing two student groups, one exposed to metaphor-integrated instruction and one following standard ESP methods, the research employs a mixed-methods design combining surveys, interviews, classroom observations, and formative and summative assessments. Findings reveal that metaphorical discourse significantly increased student participation, vocabulary acquisition, and critical thinking, particularly in complex or abstract scientific contexts. Metaphors also fostered collaboration and improved spoken and written communication by linking specialized content to students’ existing knowledge. Moreover, metaphor use contributed to a more inclusive and culturally resonant learning environment. The study concludes that metaphorical discourse is a powerful pedagogical strategy in ESP instruction, offering cognitive, emotional, and rhetorical benefits that extend beyond language learning.