The William H. Cross Expedition is an endowed collecting trip conducted annually by the Mississippi Entomological Museum. This year's expedition was held from 19 to 24 June 2017 at the Ouachita Mountains Biological Station (OMBS) in Polk County, Arkansas. We focused our collecting efforts on the mountainous Ouachita Mountains Biological Station, but we also collected at various sites within the Ouachita National Forest, at Queen Wilhelmina State Park, Big Fork Creek Natural Area, and Stone Road Glade Natural Area. During a five-day period, we collected 63 ant species, including five not previously reported for Arkansas: Brachyponera chinensis (Emery), Hypoponera inexorata (Wheeler), Strumigenys creightoni Smith, Syscia augustae Wheeler, and Temnothorax longispinosus (Roger).