Arabic Collections Online (ACO) is a publicly available digital library of public domain Arabic language content. ACO currently provides digital access to 17,694 volumes across 10,168 subjects drawn from rich Arabic collections of distinguished research libraries. It was founded with the support of NYU Abu Dhabi and is currently supported by major grants from Arcadia, a philanthropic fund of Lisbet Rausing and Peter Baldwin, and the Carnegie Corporation of New York. This digitization project aims to display up to 23,000 volumes from the collections of the New York University Library and partner institutions.