The complicated cognitive processes involved in natural (primary) bilingualism lead to significant cognitive development. Executive functions as a fundamental component of human cognition are deemed to be affected by language learning. To date, a large number of studies have investigated how natural (primary) bilingualism influences executive functions; however, the way acquired (secondary) bilingualism manipulates executive functions is poorly understood. To fill this gap, controlling for age, gender, IQ, and socio-economic status, the researchers compared 60 advanced learners of English as a foreign language (EFL) to 60 beginners on measures of executive functions involving Stroop, Wisconsin Card Sorting Task (WCST) and Wechsler's digit span tasks. The results suggested that mastering English as a foreign language causes considerable enhancement in two components of executive functions, namely cognitive flexibility and working memory. However, no significant difference was observed in inhibitory control between the advanced EFL learners and beginners.