Several ebolavirus species, with varying lethality rates, have caused sporadic outbreaks in Africa resulting in human disease. Ebolaviruses also have the potential for use as biological weapons. Currently, there are no licensed vaccines or therapeutics to respond to outbreaks or deliberate misuse of ebolaviruses. Vaccine or therapeutic efficacy testing of medical countermeasures against ebolaviruses requires an animal model of disease; in vitro testing in cell culture cannot reproduce the complicated balance between host-pathogen interactions required for the ultimate licensure of a countermeasure. Depending on the target of the countermeasure, demonstration of efficacy in the nonhuman primate ebolavirus disease models will most likely be required before licensure. Here, we describe the selection and use of nonhuman primates for vaccine and therapeutic studies against ebolaviruses.