The five Ocean Drilling Program Leg 171B holes (1049A, 1049B, 1049C, 1050C, and 1052E) in which mid-Cretaceous sediments were recovered allowed us to study in detail a continuous (with the exception of two zones in the Albian) planktonic foraminiferal succession from the upper Aptian to the uppermost Cenomanian. The generally excellent preservation of the material permitted the recognition of most of the standard bioevents already defined in the Tethyan Realm within the upper Aptian, Albian, and Cenomanian stages.