A key goal of university bilingual science courses is to enrich undergraduates' bilingual scientific literacy (BSL). However, very little is known about how to foster BSL. This study aimed to provide research evidence to explore the possibility that BSL can be promoted by using bilingual written argumentation when Socrative® is treated as an immersive participation tool. To test our hypothesis, we intervened a university Spanish-English bilingual Biology course. Fifty-two undergraduates (25 females and 27 males, 16-25 years old) were: (1) presented with argumentative questions requiring application of concepts covered in lectures, (2) asked to write a Spanish-English bilingual argumentative paragraph individually, and (3) polled for the most reasonable answer. A histogram of class responses was displayed, and undergraduates were encouraged to: (4) discuss the question in pairs, (5) write a Spanish-English bilingual argumentative paragraph in pairs, and (6) be polled for the most reasonable answer. Undergraduates' paragraphs were the subject of peer critique and useful feedback throughout the Spanish-English bilingual science course. The findings suggest significant benefits for providing undergraduates with opportunities and support to written argumentation in both English and Spanish. The outcomes of this study carry important policy implications in light of the growing university bilingual practices around the world.