The Headquarters Supreme Allied Commander Transformation and the Science and Technology Organization co-hosted the 15th NATO Operations Research and Analysis (OR&A) Conference on 18 - 20 October 2021. The conference was held virtually due the restrictions caused by the Covid-19 pandemic. This year’s conference theme was “Decision Advantage in The Information Age”. The Programme Committee encouraged the submission of any papers relevant to the theme, particularly decision making and analysis methods related to the NATO enterprise. Papers on other subjects describing emerging OR&A techniques as well as analytical case studies and best practices were also welcome. The annual OR&A conference serves as an integral component to the continuous development of the NATO OR&A Community of Interest. It builds upon previous conferences and workshops, and assembles esteemed members of the profession from across numerous organizations that include NATO commands and agencies, national defense analysis and research organizations, centers of excellence, academia, and industry.