In support of the WHO response to the Ebola crisis, NIBSC is undertaking a project to develop an International Standard for use in the calibration and control of Ebola antibody assays. The availability of International Standards (IS) for antibodies would facilitate the standardization of Ebola serological methods used in epidemiological studies to measure past or present Ebola virus disease and in vaccinology studies to measure antibodies elicited by vaccination in humans. In the absence of such standards, individual laboratories apply their own reference standards which are not harmonized with other laboratories and methods and thus cannot serve to improve the reproducibility between laboratories. Recommendations made by participants attending the Technical Workshop on the Standardisation of Serological and PCR assays for the detection of Ebola virus (NIBSC, UK, 5-6 March 2015), included the urgent prioritization of the development of an interim Ebola standard for serology assays while perusing the longer-term goal of establishing an International Standard according to published WHO guidelines and formally endorsed by the WHO Expert Committee on Biological Standardization (ECBS). This report describes the development and worldwide collaborative study evaluation of a panel of candidate Ebola antibody preparations for the selection of the most appropriate candidate to serve as the interim WHO standard for Ebola antibody assays.