Arabic Collections Online (ACO) is a publicly available digital library of public domain Arabic language content. ACO currently provides digital access to 10,042 volumes across 6,265 subjects drawn from rich Arabic collections of distinguished research libraries. Established with support from NYU Abu Dhabi, and currently supported by major grants from Arcadia, a charitable fund of Lisbet Rausing and Peter Baldwin, and Carnegie Corporation of New York, this mass digitization project aims to feature up to 23,000 volumes from the library collections of NYU and partner institutions. These institutions are contributing published books in all fields—literature, business, science, and more—from their Arabic language collections.