Thomas Jefferson apparently could speak in four different languages. When traveling through Holland and the Rhine Valley in 1788, Jefferson wrote that "there was not a person to be found in Duysberg who could understand either English, French, Italian or Latin. So I could make no enquiry."1 Later that year, in composing hints for American travelers in Europe, Jefferson warned, "I could find no body in the village however who could speak any language I spoke, and could not make them understand what I wished to see."2
When reading alone was involved, Jefferson's skills expanded to cover two more languages, Greek and Spanish. He wrote in an 1817 letter to Joseph Delaplaine, "I was educated at William and Mary college in Williamsburg. I read Greek, Latin, French, Italian, Spanish, and English of course, with something of it's radix the Anglo-Saxon."3 In addition to the languages he lists, there is some evidence that Jefferson was attempting German.
Jefferson maintained dictionaries, vocabularies, and grammars in a number of other languages in his library. These languages included Arabic, Gaelic, and Welsh, among others. Without confirmation from Jefferson himself, however, the most we can assume is that he was "dabbling" in these languages, and never achieved a notable degree of fluency.