Two dangers to linguistic and cultural pluralism are examined: (1) that the growing power of the major national languages threatens the very existence of less commonly spoken languages, and (2) that the spread of English as a universal lingua franca threatens even the major national languages. Much attention is given to the first issue, but less to the second. The pattern is similar to that of Latin, which overtook other languages earlier in history primarily because of the political power behind it. It is proposed that Esperanto has a potentially major role in addressing this problem, particularly within the European Union, by both creating a common, democratic means of communication within the Union and stemming the rise of English. Research supporting the rationality and simplicity of Esperanto, the ease with which it is learned, and the extent to which it facilitates the learning of other modern languages is reported. (MSE)