among nonhuman primates faces two major problems. First is the great diversity in reproductive processes among animals of this order. Interspecies differences in patterns and mechanisms of reproduction are characteristic among mammals in general. These differences even among otherwise closely related animals lend a diversity to reproductive processes that appears to exceed differences found in other mammalian organ systems. The primates demonstrate their full share of this diversity. The second problem is that primate reproductive biology is relatively well known for only a few frequently-studied species, with little information on many, particularly on those more distantly related to man. And even among the best studied nonhuman primates, events during or immediately before partuntion are often not well known because the time of birth cannot be accurately predicted and frequently occurs at night. The order of primates includes 176 species