About

Brett Ashley Leeds is the Radoslav Tsanoff Professor of Political Science at Rice University. She specializes in the study of international relations, with research focusing on the design and effects of international agreements, particularly military alliances, as well as connections between domestic politics and foreign policy. Leeds is the co-author of the book Domestic Interests, Democracy, and Foreign Policy Change (Cambridge Elements in International Relations series, 2022). Throughout her career, she has received notable awards including the Karl Deutsch award in 2008, which recognizes significant contributions to the study of International Relations and Peace Research by scholars under age 40, and a lifetime achievement award from the Conflict Processes section of the American Political Science Association in 2019. Leeds has served as President of the International Studies Association during 2017-18 and as President of the Peace Science Society during 2018-2019. She currently serves as Co-Editor of International Organization. Her major research areas include international conflict and cooperation, military alliances, and the influence of domestic politics on international relations.

Research topics

• Political Science
• Business
• Computer Science
• Sociology
• Law
• Political economy
• Meteorology
• Mechanical engineering
• Market economy
• Physics
• Thermodynamics
• International trade
• Mathematics
• Engineering
• Law and economics
• Geography
• Economics

Selected publications

• What Does It Mean to Be a Reliable Ally?

  Harvard Dataverse · 2026-03-02

  datasetOpen accessSenior author

  The value of military alliances is closely tied to whether alliance members will uphold their commitment if the treaty is invoked. Doubt about the reliability of an alliance can encourage aggression from rivals and, potentially, leave a state abandoned and fighting alone. Leveraging historical data on alliances and war, scholars have produced a variety of estimates of the reliability of alliances over time. We collect updated data on alliance reliability, highlighting some of the critical definitions and coding rules that impact assessments of reliability. We produce several different estimates of reliability at two levels of analysis (the alliance and the ally) using different data sources. We estimate that about two-thirds of the alliances invoked by war over a 200-year period were fulfilled, and about one-third violated. We note, however, that in the post-WWII period, alliance reliability, particularly among multilateral alliances, is lower than in prior eras. The lower estimate for multilateral alliance reliability after 1945 is driven by a small number of closely related cases, but still raises many questions for future research about potential changes in alliances and war that lead to different patterns in observed reliability.

  PublisherDOI

• What Does It Mean to Be a Reliable Ally?

  International Studies Quarterly · 2026-01-09

  articleSenior author

  Abstract The value of military alliances is closely tied to whether alliance members will uphold their commitment if the treaty is invoked. Doubt about the reliability of an alliance can encourage aggression from rivals and, potentially, leave a state abandoned and fighting alone. Leveraging historical data on alliances and war, scholars have produced a variety of estimates of the reliability of alliances over time. We collect updated data on alliance reliability, highlighting some of the critical definitions and coding rules that impact assessments of reliability. We produce several different estimates of reliability at two levels of analysis (the alliance and the ally) using different data sources. We estimate that about two-thirds of the alliances invoked by war over a 200-year period were fulfilled, and about one-third violated. We note, however, that in the post-WWII period, alliance reliability, particularly among multilateral alliances, is lower than in prior eras. The lower estimate for multilateral alliance reliability after 1945 is driven by a small number of closely related cases, but still raises many questions for future research about potential changes in alliances and war that lead to different patterns in observed reliability.

  PublisherDOI

• The Future of Global Governance and World Order

  International Organization · 2025-11-20 · 2 citations

  articleOpen access1st author

  Abstract This special issue of International Organization is composed of fifteen short essays that consider how longer-term trends (including the rise of China, the anti-globalization backlash, the rise of populism, the emergence of new technologies, the slowing or reversal of democratization in many countries, and the existential threat of climate change), along with recent developments in US foreign policy, are likely to affect the future of global governance and world order. The contributors consider a variety of different issue areas, as well as cross-cutting trends. Some contributors anticipate significant change; others predict incremental change; and still others expect mostly continuity. The collection suggests a future research agenda focused on the impact of long-term trends and immediate shocks on local, regional, and global equilibria.

  PublisherOA PDFDOI

• Alliances and Civil War Intervention

  International Studies Quarterly · 2024-09-14

  article

  Abstract Governments have a number of structural advantages over rebel groups in civil wars, one of which is their greater ability to make credible international commitments. Governments can use foreign policy commitments to incentivize other states to provide them military support or deny support to their rebel groups. We analyze international intervention in civil conflicts between 1975 and 2017 and find that some kinds of alliances are associated with pro-government intervention, but all alliances are not equal. Alliances with consultation commitments are associated with interventions that provide materiel, training, intelligence, and/or other forms of non-troop support, while defense pacts are associated with both troop and non-troop support. Members of nonaggression and neutrality pacts are not more likely to intervene to support the government but are less likely to provide support to anti-government forces. We argue that alliances are not simply proxies for common interests; they sometimes involve specific bargains designed to aid a government in defeating rebels. Our evidence suggests that these agreements are successful at incentivizing the intended behavior. Governments use international security policy to protect the status quo domestically as well as internationally, and this affects our understanding both of civil wars and of alliance politics.

  PublisherDOI

• INO volume 77 issue 3 Cover and Front matter

  International Organization · 2023

  • Computer Science
  • Computer Science
  • Business

  An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

  PublisherOA PDFDOI

• Domestic Interests, Democracy, and Foreign Policy Change

  2022 · 39 citations

  1st authorCorresponding
  • Political Science
  • Political Science
  • Political economy

  When new leaders come to office, there is often speculation about whether they will take their countries' foreign policies in different directions or stick to their predecessors' policies. We argue that when new leaders come to power who represent different societal interests and preferences than their predecessors, leaders may pursue new foreign policies. At the same time, in democracies, leadership selection processes and policymaking rules blunt leaders' incentives and opportunities for change. Democracies thus tend to pursue more consistent foreign policies than nondemocracies even when new leaders with different supporting coalitions assume office. Statistical analyses of three distinct foreign policy areas – military alliances, UNGA voting, and economic sanctions – provide support for our argument. In a fourth area – trade – we find that both democracies and nondemocracies are more likely to experience foreign policy change when a new leader with a different supporting coalition comes to power. We thus conclude that foreign policy responds to domestic political interests, and that, even as the interests supporting leaders change, democracies' foreign policies are no less stable than those of nondemocracies and often exhibit greater consistency.

  PublisherDOI

• Editors’ Note

  International Organization · 2022-01-01

  article1st authorCorresponding

  An abstract is not available for this content. As you have access to this content, full HTML content is provided on this page. A PDF of this content is also available in through the ‘Save PDF’ action button.

  PublisherDOI

• Replication Data for: Domestic Interests, Democracy, and Foreign Policy Change

  Harvard Dataverse · 2022-03-19

  datasetOpen access1st authorCorresponding

  These files contain replication data and code for the 2022 Cambridge Element entitiled Domestic Interests, Democracy, and Foreign Policy Change, by Brett Ashley Leeds and Michaela Mattes.

  PublisherDOI

• INO volume 76 issue 3 Cover and Front matter

  International Organization · 2022-01-01

  articleOpen access

  An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

  PublisherOA PDFDOI

• Threats at Home and Abroad: Interstate War, Civil War, and Alliance Formation

  International Organization · 2021 · 16 citations

  Senior authorCorresponding
  • Political Science
  • Political Science
  • Sociology

  Abstract In the current era, many of the military threats that state leaders face come from domestic and transnational nonstate actors. Military alliances are recognized as an important policy strategy to counter military threats, but existing research has primarily been focused on threats from other states and has difficulty uncovering a consistent relationship between external threat and alliance formation. We argue that this discrepancy arises from the failure to recognize that many threats are not external to the state. We contend that alliance formation is motivated both by external threats from other states and by internal threats that make civil conflict more likely. Moreover, we argue that leaders design alliance obligations differently when faced with internal threats. An empirical analysis of alliance formation from 1946 to 2009 shows that while external threats motivate the formation of defense pacts, internal threats encourage the formation of consultation pacts. Internal threats with the greatest potential for internationalization also encourage the formation of neutrality/nonaggression pacts. This research deepens our understanding of how states design security policies to deal with the threats posed by nonstate actors, a salient concern of leaders in the twenty-first century, and helps us to understand the variety of alliance obligations that we observe.

  PublisherDOI

Recent grants

• Collaborative Research: Interests, Institutions, and Foreign Policy Change

  NSF · $235k · 2009–2013

Frequent coauthors

• J. Lawrence Broz

  Cambridge University Press

  44 shared

• Ḿanaging Editor

  University of Edinburgh

  44 shared

• Martha Finnemore

  43 shared

• Layna Mosley

  The Ohio State University

  39 shared

• ̧e Zarakol

  Princeton University

  38 shared

• Joel W. Simmons

  38 shared

• B. G. Peter

  University of Arkansas at Fayetteville

  38 shared

• Rosendorff Associate

  Princeton University

  38 shared

Labs

• Brett Ashley Leeds LabPI

Education

• Ph.D., Political Science

  Emory University

  1998

• BA, Political Science

  University of North Carolina at Chapel Hill

  1991

Awards & honors

• Karl Deutsch award (2008)
• lifetime achievement award from the Conflict Processes secti…