These include ambassadors, agency directors, combatant commanders, members of the Joint Chiefs of Staff, and university president.

Faculty has included Condoleezza Rice, Caspar Weinberger, Kathleen Hicks, Michèle Flournoy, Bernard Lewis, Francis Fukuyama, and Peter Singer, among others.

[2] Its three founders were Suzanne Berger, Jake W. Stewart, and Mitzi Wertheim who wanted to improve on the national security community's perspective in the 1970s and 1980s.

[2] Its initial design was to "provide a unique educational perspective for senior military and civilian officials and to afford an opportunity for frank and challenging exchanges of ideas between policymakers, university scholars, and Seminar XXI Fellows".

[7] The seminar educates national security professionals across multiple government and non-governmental organizations "with significant potential to move into key decision-making roles in the next 5–10 years".

[8] The curriculum for the 2022–2023 academic year included topics such as: Religion, Identity politics, and Civil wars; Realism, Liberalism, and China; Pandemic Security and COVID-19; Cybersecurity and Biosecurity; Japan, Europe, and South Korea – US Alliance Relationships; National Economies in a Globalized World; Iran, Turkey, and Israel; and U.S. National Security Policy.

The analytic problem solving skills and personal interaction with other students from across the U.S. Government, as well as several non-governmental organizations, has proven tremendously valuable for a professional military officer thinking through the complex security issues facing our country."

Ambassador Harry Thomas called it a "unique opportunity" and "an enriching experience which allowed me to bring new proposals to the never-ending challenges we face in the Department of State.

"[14] Foreign Service officer Meghan Gregonis called the seminar a "first rate program" and noted that it "broadened my perspective, and ... sharpened my focus".