(FORTUNE Magazine) – When Jean-Marie Descarpentries, the burly boss of French packaging group Carnaud, paid $1.4 billion for Britain's Metalbox Packaging last October, he acquired more than just a business. He bought himself a new corporate language. Starting in April, all Carnaudians began writing official memos and conducting many meetings in the tongue of Milton, Shakespeare, and Adam Smith. Carnaud is merely the latest to join a growing band of multinationals that have declared English their ''official'' corporate tongue. Why not? English is a common second language in many countries. Philips, the Dutch electronics giant, took the step back in 1983. When Brown Boveri of Switzerland combined with Asea of Sweden 18 months ago to form ABB, a titan in electrical power equipment, English was declared the official corporate tongue. The Swedish executives already spoke the language well, but not their German-speaking counterparts at Brown Boveri. They were forced to switch to English -- overnight. Attendance at the Swiss company's in-house English language classes promptly doubled. Within a number of voracious Asian exporters -- among them Acer, Taiwan's fast-growing personal-computer maker -- English has long accounted for the bulk of spoken and written messages.