This study aims to investigate whether the representation of a third language in the mind provides an advantage in executive control processes compared to bilinguals. To this end 10 high proficient bilingual Turkish-English and 10 high proficient trilingual Turkish-English-German speakers were given a language control demanding task and participants' response times (RTs) and the accuracy of their responses were analyzed. The results showed that the bilingual group responded to their L2 (English) statistically slower than their L1 (Turkish) while the trilingual group did not show any difference in RTs in their three languages. It is also found that the trilingual participants were far more accurate in their responses. Based on these results it is hypothesized that a third language system represented in the mind might have the effect of promoting experience or regulation costs of the executive control system.