How were New World drugs received and understood in early modern England? In the seventeenth century, England’s first empire was being established and an increasing abundance of medicinal plants arrived in London from across the Atlantic. In this thesis, I argue that commercial and political imperatives drove the production, trade and consumption of New World medicines. I explore trends in the drug trade across the early modern period to identify how the scale and diversity of American medicines fluctuated in the English market. I recognise a critical juncture in the 1650s with a change in political institutions and the collapse of the colonial tobacco economy. In the case of Virginia, merchants and colonial statesmen advised the Parliamentarian government on new forms of plantation governance and economic development. Their recommendations included investment in perceived lucrative new commodities, such as sassafras, sarsaparilla and other medicinal plants. As the supply of American drugs expanded in the English market from the 1650s to the 1680s, medical writers became more engaged in the recommendation of New World medicaments for the treatment of diseases, including scurvy and venereal diseases. I consider the process of knowledge negotiation and commercial policymaking in issues surrounding the trade, propagation and transplantation of American medicinal plants into England during the late seventeenth century. The availability and consumption of New World drugs became commonplace by the early eighteenth century, and they could even be accessed by schoolboys and pensioners at charitable institutions. To formulate this narrative, I employ an integrated historical approach, drawing from economic, colonial, intellectual and medical history. I examine customs records, first-hand colonial accounts, printed books and pamphlets, manuscript commonplace books, letters, prescription lists and medical journals. This study contributes to research programmes on English colonial development, global commodities, the Columbian exchange and the early modern medical marketplace.