This article examines systematically the growth of the English language from the year 252 ce through 1985. Using a data set collected from the CD-ROM version of the second edition of the Oxford English Dictionary, we characterize the time series of new words added to the language, by year, calculate rates of growth and obsolescence, and disaggregate the data by parts of speech. Economic models of language growth over a modern period (1830-1969) are then estimated. We report evidence that language is a network good (the number of new English words is negatively related to population and to gross national product), that additions to the language are retarded by government growth, that the stock of words in use is strongly influenced by fore...