This study explores the interface between learner beliefs and multilingualism in the under-researched English as a Foreign Language (EFL) context of Turkey. The study investigates the underlying constructs of a modified Beliefs about Language Learning Inventory (BALLI) completed by 168 EFL learners in Turkey using an exploratory factor analysis (EFA). One-way analyses of variance (ANOVAs) were run using two different group divisions for the independent variables: one analysis was run using the groups division of bilinguals versus multilinguals and the second analysis was run using the Perceived Positive Language Interaction (PPLI) group division. These analyses reveal significant differences with both categorizations. That is, knowledge of languages other than English, as well as seeing positive interactions between languages studied, can have a significant effect on learners' beliefs. The uniqueness of the study lies in its discussion of multilingualism within the realm of Dynamic Systems Theory (DST) in the Turkish EFL context. The results of this study underscore the impact of multilingualism on language learning and promote the study of interaction between multilingualism and learner beliefs in diverse contexts.