The evolutionary development of Mesozoic planktic foraminifera is almost exclusively restricted to the Cretaceous Period. Diversity is relatively low until the Late Cretaceous (Turonian to Maastrichtian) when numerous architectural forms are found in the record. Just as remarkable, and more so to this author, is the nearly complete extinction of the group at the end of the Maastrichtian. My purpose will be to attempt to briefly categorize the major areas of study and to describe the numerous problems yet to be solved by workers in the field.