The language in which treaties are written affects how widely and deeply treaty obligations are understood and, hence, followed.

Of course, many problems arise when the treaty does not have the same meaning in different languages.

The focus of this article is a different aspect of language in treaties--the choice of language or languages as official text or texts of bilateral treaties. Some research has addressed the broader issue of multiple use of languages in international organizations and multilateral treaties, but bilateral treaties have received scant attention. This inattention likely stems from the difficulty of examining the treaty practice of more than 150 states in tens of thousands of treaties, a difficulty now largely overcome by modern database management techniques. This article examines a lengthy period of state practice, the half century between 1920 and 1970, in order to describe and understand language choices. At first blush, this may seem like much ado about nothing. Of course, it is the content, not the choice of official text, that matters most.

However, the approach taken here, based as it is on an enormous amount of state practice, can elucidate a number of important issues:

*To what degree has English taken over the lingua franca role previously played by Latin and French?

*Is there any political dimension to language choice?

*Has the rise of the United States and the Soviet Union as superpowers after World War II been accompanied by an increased use of English and Russian as official texts?

*Is the emergence of the Third World as a major force in the international system reflected in languages used in treaties?