The present paper examines lexicon organization and lexical uniqueness through a lexicalavailability task. Previous research has concentrated on exploring via word association testshow learners organize their L1 and L2 lexicons. Additionally, the closeness between the nativeand the L2 lexicons are also object of analysis in research. Lexical uniqueness has also beenused as a measure to determine “nativeness”. In the present study, we had two groups ofGreek B1 and C1 level learners of Spanish FL answer a lexical availability task and comparedtheir results with those of a group of native speakers. We found that proficiency level is crucialin the determination of lexical uniqueness and lexicon organization via lexical associationsobtained with a lexical availability task. Furthermore, our results revealed that thematic fieldis a relevant factor in speakers’ associative behaviour and lexicon organization. Results arediscussed in light of previous research findings and pedagogical implications are proposed.