This study explores how proficiency in a second language determines the way that lexical and semantic representations are functionally connected in bilingual memory by testing three groups of participants (beginning and intermediate Spanish-Catalan learners and highly proficient bilinguals). The experiment reported examines how form and semantic manipulations affect the performance of these groups in a translation recognition task using three types of word relations (very close and close semantically related word pairs and form-related pairs). The results reveal that form manipulation affects the performance of the three participant groups, whereas the influence of semantic relations depends on the participants’ level of proficiency. Results are discussed within the framework of the Revised Hierarchical Model (Kroll & Stewart, 1994).