About

Lilliana Mason is SNF Agora Institute Professor of Political Science at Johns Hopkins University. Her research focuses on partisan identity, partisan bias, social sorting, and American social polarization. She has authored books including 'Uncivil Agreement: How Politics Became Our Identity' and co-authored 'Radical American Partisanship: Mapping Violent Hostility, Its Causes, and the Consequences for Democracy.' Mason received her PhD in political psychology from Stony Brook University and her BA in politics from Princeton University. Her work has been published in prominent journals such as the American Political Science Review, American Journal of Political Science, Public Opinion Quarterly, and Political Behavior, and has been featured in media outlets including the New York Times, the Washington Post, CNN, and National Public Radio. Her research has been supported by organizations including the National Science Foundation, the Sloan Foundation, the Facebook Research Integrity Group, and the Democracy Fund.

Research topics

• Political Science
• Law
• Sociology
• Social Science
• Psychology
• Political economy

Selected publications

• Gun ownership for political protection or armed political expression: a nationally representative analysis of differences in 2025 vs. 2023

  Injury Epidemiology · 2026-01-19

  articleOpen access

  BACKGROUND: Reasons for gun ownership have shifted from primarily for hunting, to protection from other people, and increasingly for concerns about political violence. In 2023, these reasons differed by party affiliation. In the aftermath of the 2024 Presidential election, the objective of this study was to compare gun owners' reasons for gun ownership in January 2025 vs. 2023, overall and by political party affiliation. METHODS: We analyzed two waves of gun owning respondents to the National Survey of Gun Policy (n = 2,003). In both waves, fielded 1/4/23 - 2/6/23 and 1/6/25 - 1/24/25, respondents identified personally important reasons for gun ownership from 10 potential reasons (e.g., at-home protection, out-of-home protection, protection from police, ideological conflict, hunting or recreation). We calculated weighted proportions to generate nationally representative estimates and compared reasons for gun ownership in 2025 to 2023 overall and by political affiliation (i.e., Republican, Democrat, or Independent). RESULTS: In 2025 (vs. 2023), more gun owners valued gun ownership "for protection at demonstrations, rallies, or protests" (42% vs. 35%) and for hunting (81% vs. 74%), but fewer valued ownership "to advance an important political objective" (22% vs. 35%). Increases were largely driven by Republican gun owners, who also rated higher at-home protection (97% vs. 93%) and protection against police violence (34% vs. 25%). Fewer Republican, Democrat, and Independent gun owners valued ownership "to advance an important political objective." CONCLUSIONS: As political violence escalated nationally, larger portions of gun owners rejected such violence, while also seeking to protect themselves from it. Safety and policy implications are discussed.

  PublisherDOI

• Mind the Gap: Partisan Bias in Justifying Political Violence in the United States

  Public Opinion Quarterly · 2026-03-21

  articleOpen access

  Abstract Political polarization in America has intensified beyond mere disagreement to what scholars characterize as sectarianism—a condition where partisan identity fundamentally shapes moral judgments. A key marker of sectarianism is asymmetric moral standards for violence, where aggression against political opponents is considered more justified than identical violence targeting one’s own group. Using a survey experiment featuring a realistic political rally scenario, we find compelling evidence in support of such sectarianism: partisan bias in the US extends to evaluations of political violence. By manipulating the partisan affiliations of perpetrators and targets, as well as provocation severity, we find that both Democrats and Republicans exhibit substantial and symmetrical partisan bias. This double standard is particularly pronounced among strong partisans, who are nearly three times more likely to justify violence against the opposition than violence targeting their own party. These results extend sectarianism theory beyond policy preferences to physical violence, suggesting that partisan identity now functions as a powerful perceptual filter that can legitimize political aggression when directed at opponents.

  PublisherDOI

• Mind the gap: Partisan bias in justifying political violence in the United States

  2025-11-24

  articleOpen accessSenior author

  Political polarization in America has intensified beyond mere disagreement to what scholars characterize as sectarianism – a condition where partisan identity fundamentally shapes moral judgments. A key marker of sectarianism is asymmetric moral standards for violence, where aggression against political opponents is considered more justified than identical violence targeting one's own group. Using a survey experiment featuring a realistic political rally scenario, we find compelling evidence in support of such sectarianism: partisan bias in the US extends to evaluations of political violence. By manipulating the partisan affiliations of perpetrators and targets, as well as provocation severity, we find that both Democrats and Republicans exhibit substantial and symmetrical partisan bias. This double standard is particularly pronounced among strong partisans, who are nearly three times more likely to justify violence against the opposition than violence targeting their own party. These results extend sectarianism theory beyond policy preferences to physical violence, suggesting partisan identity now functions as a powerful perceptual filter that can legitimize political aggression when directed at opponents.

  PublisherDOI

• How to Measure Public Support for Political Violence

  Public Opinion Quarterly · 2025-12-06

  articleSenior author

  Abstract With low but rising levels of violent political threats and violent acts by civilians in the United States, researchers increasingly want to measure violent public views—fearing the erosion of collective norms inhibiting violence while also regarding individual attitudes as a risk for rare violent action and more common forms of aggressive political behavior. But how should violent views be measured and interpreted? Drawing on our decade-plus researching these views with several dozen questions and a catalogue of related work by others, we provide a practical measurement guide for assessing violent political views with extensive new observational and experimental illustrations that also make important methodological and substantive contributions to the field. We provide considerations for choosing good measure(s): empirically informed measurement principles, general and specific question evaluations, a deep dive into question design, reliability, and validity, and more. The Supplementary Material also catalogues a century of violence questions and more published works.

  PublisherDOI

• Cool Citizens? How Affectively Unpolarized Citizens View and Participate in Democracy

  2025-06-24 · 1 citations

  preprintOpen accessSenior author

  Does affective polarization change how citizens view and participate in democracy? We posit that the answer to this crucial question depends on how affectively unpolarized citizens view and participate in democracy. Yet, the standard operationalization of affective polarization––measuring sympathy ratings for one party relative to another––does not differentiate between people’s absolute sympathy ratings for the parties, which may mask essential heterogeneity among unpolarized citizens. This paper theorizes the methodological origin of this heterogeneity, describes it, and highlights its implications. Cluster analyses and regressions from three nationally representative surveys in the US provide three conclusions. First, substantial shares of the US population are affectively unpolarized. Second, unpolarized citizens cluster into two groups: one feeling lukewarm and one feeling cold toward both parties. Third, these unpolarized groups report diverging democratic attitudes and participation patterns. We discuss the methodological implications and the need for future research on affectively unpolarized citizens.

  PublisherOA PDFDOI

• On the Malleability of Democratic Attitudes: Do Citizens’ Views of Democracy Vary With How They Feel?

  2025-07-09

  preprintOpen accessSenior author

  How fluid are citizens’ views of democracy and its actors? Citizens widely support democracy in principle, but temporary factors like partisan considerations push many to bend these principles. To identify the limits of this malleability, we examine whether citizens’ democratic views even covary with a seemingly unrelated yet ubiquitous factor: their affective state. Drawing on multidisciplinary research, we theorize that citizens have more (less) benevolent views of democracy and its actors when feeling good (bad). Two studies with nationally representative samples from the Netherlands and the US––analyzing sixteen waves of naturally varying and experimentally induced affective states––test this prediction. We find that citizens’ affective states shape how they evaluate democracy and its actors, but these effects are limited to long-term variation in how they feel. This evidence implies that citizens’ democratic views are––though even more fluid than recently shown––nonetheless robust to immediate variations in affective states.

  PublisherDOI

• Social sorting and affective polarization

  Edward Elgar Publishing eBooks · 2025-07-08

  book-chapter1st authorCorresponding
  PublisherDOI

• Threats as Political Communication

  Political Communication · 2023-10-18 · 9 citations

  articleSenior author

  Click to increase image sizeClick to decrease image size Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationNotes on contributorsNathan P. KalmoeNathan P. Kalmoe is executive director of the Center for Communication and Civic Renewal in the School of Journalism and Mass Communication at the University of Wisconsin, Madison. He has written three scholarly books, two dozen academic articles, and many public essays on contentious politics and democratization, with particular focus on messaging effects, partisanship, violence, identity, and ideology to inform national discussions. His research on mass politics integrates political science, communication, psychology, and history with a wide range of social science methods. Kalmoe's work has been featured in The New York Times, The Washington Post, The Atlantic, and other popular outlets. He was associate professor of political communication at Louisiana State University before moving home to Wisconsin.Lilliana MasonLilliana Mason is SNF Agora Institute Associate Professor of Political Science at Johns Hopkins University. She is co-author, with Nathan P. Kalmoe, of Radical American Partisanship: Mapping Violent Hostility, Its Causes, and the Consequences for Democracy (University of Chicago Press, 2022), and author of Uncivil Agreement: How Politics Became Our Identity (University of Chicago Press, 2018). Her research combines the fields of social psychology, sociology, and political science to examine American political behavior. Her work on partisan identity, partisan bias, social sorting, and American attitudes toward political violence has been published in journals such as American Political Science Review, American Journal of Political Science, Journal of Politics, Public Opinion Quarterly, and Political Behavior, and featured in media outlets including the New York Times, the Washington Post, CNN, and National Public Radio.

  PublisherDOI

• Political Identities

  Oxford University Press eBooks · 2023-09-18

  book-chapter1st authorCorresponding

  Abstract This chapter examines the nature and consequences of partisan and ideological identities. Such identities sit uncomfortably with normative ideals of democratic behavior because they can result in political behavior that is at odds with the ideal democratic citizen as rational, objective, and fully informed. Nonetheless, social identification with political groups drives political behavior and informs the study of citizens’ participation, organization, and judgment. This chapter reviews the application of social-psychological theories concerning social identity and intergroup conflict to political behavior. More specifically, the chapter reviews evidence on the effects of political identities on information processing, political action, political emotions, and prejudice against political opponents. The chapter makes clear that while voter political behavior is not often “rational” from an individual economic perspective, it is in line with predictable psychological motivations.

  PublisherDOI

• Political Identities

  Oxford University Press eBooks · 2023-09-18 · 4 citations

  book-chapter1st authorCorresponding

  Abstract This chapter examines the nature and consequences of partisan and ideological identities. Such identities sit uncomfortably with normative ideals of democratic behavior because they can result in political behavior that is at odds with the ideal democratic citizen as rational, objective, and fully informed. Nonetheless, social identification with political groups drives political behavior and informs the study of citizens’ participation, organization, and judgment. This chapter reviews the application of social-psychological theories concerning social identity and intergroup conflict to political behavior. More specifically, the chapter reviews evidence on the effects of political identities on information processing, political action, political emotions, and prejudice against political opponents. The chapter makes clear that while voter political behavior is not often “rational” from an individual economic perspective, it is in line with predictable psychological motivations.

  PublisherDOI

Frequent coauthors

• Julie Wronski

  University of Mississippi

  25 shared

• John Kane

  New York University

  24 shared

• Nathan P. Kalmoe

  University of Wisconsin–Madison

  14 shared

• David Karol

  University of Maryland, College Park

  7 shared

• Jared McDonald

  7 shared

• Leonie Huddy

  5 shared

• Eli J. Finkel

  Stanford University

  1 shared

• Shanto Iyengar

  Stanford University

  1 shared

Education

• PhD, Political Science

  Stony Brook University

  2013

• BA, Politics

  Princeton University

  2000

Awards & honors

• Supported by the National Science Foundation
• Supported by the Sloan Foundation
• Supported by the Facebook Research Integrity Group
• Supported by the Democracy Fund