When we learn another language we soon discover that some objects that we hold in the same category belong to different categories in the new language and, reciprocally, that some categorical distinctions in our native language do not apply in the new language. For instance, taza in Spanish refers to both ‘cup’ and ‘mug’ in English. Here, using event-related brain potentials in Spanish-English bilinguals, we will study the neural correlates of categorical distinctions that arise from differences in terminology between languages. The first experiment will test the plasticity of the bilingual conceptual system by comparing perceptual processing of objects belonging to the same or different categories across languages. A second experiment will determine whether variations in conceptual representations can be modulated online by language context. The results will provide fundamental new insights into language-cognition interactions in bilinguals.