This paper will explore attempts by the authorities in Ottoman Algiers in the later 17th and 18th centuries to define and regulate a commercial space at the intersection between the Ottoman Mediterranean and the wider waters beyond. Through examining the Ottoman Turkish, English, and French treaty texts between Algiers and foreign states, correspondence of the deys with their Ottoman masters and European governments, and mercantile correspondence, several key themes emerge in understanding Algiers as a commercial power in the 18th century. As a frontier province of the Ottoman Empire, but also a de-facto independent state with its own foreign and commercial policy, Algiers developed practices with that attempted to balance two realities. On the one hand, the Algerian authorities wanted to enforce military authority over the Western Mediterranean, acting as a kind of security screen to protect its own interests and the Ottoman waters beyond against common enemies, monitoring commerce for potential contraband. On the other, it aimed to encourage commerce to, from, and via Algiers, as well as protecting the interests and security of Algerian merchants. Agreements and correspondence between Algiers and foreign powers show a wide range of rights on both sides, but also indicate a consent that security concerns necessarily had to play a role in the daily function of peaceful commerce. Whereas the historiographical focus has usually been, and often remains, focused on the depredations of the so-called “Barbary corsairs” against Western European shipping, an examination of the Algerian and Ottoman side of the sources indicates a more complex picture of trying to maintain peaceful commerce and friendly relations in a maritime space that was almost constantly dominated by conflict. The complications of this system became readily apparent from the beginning of the eighteenth century, as French and British privateering against each other’s shipping resulted in attacks against Algerian merchants and their cargos. The limited means of redress available to either the Algerian authorities or their merchants indicates shifting attitudes towards Algiers as a Mediterranean political and economic power in the 18th century.