This pilot study is based on the assumption that the selection of lexical items reveals the level of conceptual fluency in the target language. This assumption is supported by the model of the Dual Language System of Kecskes and Papp (2000) in which the word is an interface between the conceptual level and lexical level which blends information from both levels. To support the hypothesis the authors collected production data in an immersion school on the outskirts of Barcelona, Spain, where the students' L1 is Catalan, L2 is Spanish, and FL is English. All three languages are used as a medium of instruction. Students were asked to read articles in one language and summarize the content in their other language (Catalan text had to be summarized in English, and English text was summarized in Catalan). Data analysis based on length of summary, presence of key words and use of content word equivalents confirmed that there is a direct link between lexical choice and conceptual fluency in the FL.