Matthias James O'Conway (1766-1842) was born in Ireland but lived all his adult life in the New World. His travels ranged from the Northwest Wilderness of the Ohio Frontier to the Spanish possessions of Cuba and Louisiana. He eventually settled in Philadelphia, then the United States capital. O'Conway made his living as a translator and teacher of languages and left a number of important publications and manuscripts in philology and lexicography. He was an influential member of the Catholic community in the early United States, being an early supporter of Elizabeth Seton, first United States citizen to be canonized. O'Conway had a large family, several of whom had interesting lives in their own light. This account of O'Conway provides a new perspective on Irish emigrants in the early years of the American Republic.