The aim of the paper is to explore the appearance of positive and negative lexical transfer of plurilingual learners in English vocabulary acquisition. Cross-linguistic influences in the study are examined by word translation tasks from Croatian into English, including true, partial, and deceptive cognates or false friends in English, German, and Italian. The results have revealed different language dominances and positive or negative transfer manifestation. Lexical transfer from L4 German is manifested positively, but the Italian language seems to play a dominant role in the acquisition of English vocabulary. The effect of Croatian is manifested both positively and negatively. The study has confirmed previous psycholinguistic studies on the complexity of lexical connections in plurilingual learners and the dynamic interaction of various learning-based factors, such as language recency, proficiency, exposure to languages, the order in which languages are learned, and the formal context in language learning
