20240512 Would Electing More Women Image 03

Would Electing More Women Make the U.S. Congress Less Polarized?

With growing ideological polarization in the electorate and among U.S. Congress members, the view that electing more women would help solve partisan gridlocks has also grown especially popular. In this policy brief we review recent evidence on gender differences in cooperative behavior among legislators and argue that the prediction that a more female U.S. Congress would be less polarized does not find strong support in the data. While, in the past, Republican women have cooperated more with Democrats than their male colleagues we find evidence that this was due to higher ideological proximity between Republican women and Democrats rather than gender per se. Among Democrats, women actually appear to cooperate less with the opposite party than their male colleagues. Moreover, in recent years gender differences in ideology among Republicans have been narrowing, which also reduce gender differences in cooperation with the opposite party.

Gender Differences in Cooperative Behavior

Observers of U.S. politics have repeatedly reported increasing polarization in the U.S. electorate and Congress over the last decade, with growing concerns that the partisan gridlocks that have impaired Congress’ activities in the last two years will only grow after the 2024 elections. At the same time, it is widely believed that electing more women to the U.S. Congress would help reduce partisanship among legislators and promote cooperation across party lines. For instance, a report by the Center for American Women and Politics found that “collaboration by women across party lines is often fostered by participation in bipartisan, single-sex activities […] which can lead to policy collaboration” (Dittmar et al. 2017). These beliefs are rooted not only in anecdotal evidence but also in academic studies that, through laboratory experiments, have shown that women tend to cooperate more than men (cooperation is considered as working in a team to achieve a common good). However, this finding is not universal across settings and studies (Balliet et al. 2011), which suggests some caution in foreseeing fewer partisan gridlocks when more women are elected. Moreover, while laboratory experiments are a very important tool to discover patterns of human behavior in “ideal” conditions, testing for the robustness of experimental findings in real-world settings is a necessary step to draw definite implications for society-level outcomes.

What then is the research-based evidence on women’s willingness to cooperate with opposite parties as legislators?

Do Women in the U.S. Congress Cooperate More With the Opposite Party Than Men?

The proportion of women in Congress continues to be low, currently standing at 29 percent of the House of Representatives and 25 percent of the Senate. However, women’s representation has massively increased over time, especially since the 101st Congress, which was elected in 1989 (see Figure 1). This change has prompted researchers to investigate the effects of women’s different approaches to competitive and cooperative situations on the day-to-day working of Congress.

In examining the dynamics of legislative cooperation, contrasting viewpoints shed light on the role of gender in policymaking. Volden et al. (2013) find that women’s increased cooperativeness especially helps female lawmakers from minority parties who are able to sustain their bills throughout the legislative process, while more obstructive Congress members fail to find consensus. Offering an alternative explanation, Anzia and Berry (2011) show that female lawmakers indeed sponsor and co-sponsor more bills than male lawmakers but argue that this is due to only the best and most ambitious women entering Congress due to discrimination.

Figure 1. Women in Congress over time.

Source: Bagues et al. (2023), data from the Congressional Research Service.

This early work highlights the importance of studying gender differences in Congress overall and by party, while comparing women and men who have similar characteristics and are elected in comparable districts.

In a recent study, Gagliarducci and Paserman (2022) adopt several empirical strategies to assess the extent to which largely comparable women and men in Congress behave differently in terms of cooperativeness. Their measure of cooperation is the number of co-sponsors that women and men respectively attract on their bills, and what share of these co-sponsors that are from the opposite party. Each bill presented to the U.S. Congress has a main sponsor and can have an unlimited number of co-sponsors. These co-sponsors attract support for the bill and aid its passage through the necessary legislative steps. Gagliarducci and Paserman (2022) consider bills proposed to the U.S. Congress between 1988 and 2010 and find that among Democrats there is no significant gender gap in the number of co-sponsors recruited, but women-sponsored bills tend to have fewer co-sponsors from the opposite party. On the other hand, they establish robust evidence that Republican women recruit more co-sponsors and attract more bipartisan support on their bills than Republican men. They conclude that this pattern indicates that cooperation is mostly driven by a commonality of interest, rather than gender per se. This since during this period female Republican representatives were ideologically closer to Democrats than their male colleagues, whereas Democratic women were ideologically further away from Republicans. They proxy representatives’ ideology using information on the ideological leaning of voters in representatives’ constituency in the presidential elections. As the authors observe, these findings challenge the commonly held view that an increase in female representation in the US Congress would help solve partisan gridlock.

In a recent working paper (Bagues et al. 2023), we assess the replicability and reproducibility of these findings, given their practical relevance in the face of the upcoming 2024 Congress elections. Our work is part of a large effort promoted by the Institute for Replication to improve the credibility of social science by systematically reproducing and replicating research findings published in leading academic journals.

Using the same data and empirical strategies as in Gagliarducci and Paserman (2022), except for correcting for some data collection errors and proposing different assumptions on the empirical specifications, we virtually confirm all their original findings. Most importantly, we also extend the analysis to cover 2011-2020 to study gender differences in legislative cooperation in a context that differs in at least two relevant aspects. During this period the share of women in the House of Representatives became substantially larger and, moreover, within-party gender differences in ideology changed compared to previous decades. While Democratic female representatives are still less conservative that Democratic men, women became ideologically more similar to their male colleagues among Republicans. We reach this conclusion by proxying representatives’ ideology using information on the ideological leaning of voters in representatives’ constituency in the presidential elections, as in Gagliarducci and Paserman (2022).

Consistent with the hypothesis that gender differences in cooperation across parties are driven mainly by ideological distance, we observe that bills sponsored by female Democrats are less likely to have opposite party co-sponsors than bills sponsored by male Democrats. We also, do not observe any gender differences in bipartisan cooperative behavior among Republicans. Finally, we observe more robust evidence that during the last decade bills from both Republican and Democratic women attracted more sponsors than bills from their male colleagues.

In sum, the novel evidence from the 2011-2020 period strengthens the finding that cooperation with members of the other party is driven mainly by ideological proximity rather than gender per se.


We have reviewed the recent academic literature on gender differences in willingness to cooperate among legislators, considering the largely popular view that a more female U.S. Congress would be less polarized and thus face fewer partisan gridlocks. Such a view is particularly salient at a time of increased polarization in U.S. politics and growing representation of women in the U.S. Congress.

Overall, studies of the extent to which bills promoted by women and men in Congress attract co-sponsors from members of the opposite party invite caution in predicting fewer gridlocks from the election of more women. Women legislators do not appear to be inherently more willing to cooperate with the opposite party. Gender differences in cooperation noticed in the past seem to be mainly driven by Republican women being more likely to legislate with Democrats because of a higher degree of ideological proximity to the opposite party compared to their male colleagues. However, analysis of recent data also show that Republican women have become ideologically more aligned to their male colleague in the last decade. This suggests that as the share of women in Congress increases, their characteristics and ideological standing might also change, making it hard to predict patterns of future behavior based on the past.


  • Anzia, Sarah F., and Christopher R. Berry. (2011). The Jackie (and Jill) Robinson effect: Why do congresswomen outperform congressmen? American Journal of Political Science 55, no. 3. pp. 478-493.
  • Bagues, Manuel, Pamela Campa, and Giulian Etingin-Frati. (2022). Gender Differences in Cooperation in the US Congress? An Extension of Gagliarducci and Paserman. No. 75. I4R Discussion Paper Series, 2023.
  • Balliet, Daniel, Norman P. Li, Shane J. Macfarlan, and Mark Van Vugt. (2011). Sex differences in cooperation: a meta-analytic review of social dilemmas. Psychological Bulletin 137, no. 6. p. 881.
  • Dittmar, Kelly, Sanbonmatsu, Kira, Carroll, Susan, Walsh, Debbie, and Wineinger, Catherine. (2017). Representation Matters: Women in the U.S. Congress. Centre for American Women and Politics, Rutgers University.
  • Gagliarducci, Stefano, and M. Daniele Paserman. (2022). Gender differences in cooperative environments? Evidence from the US Congress. The Economic Journal 132, no. 641, pp. 218-257.
  • Volden, Craig, Alan E. Wiseman, and Dana E. Wittmer. (2013). When are women more effective lawmakers than men?. American Journal of Political Science 57, no. 2. pp.326-341.

Disclaimer: Opinions expressed in policy briefs and other publications are those of the authors; they do not necessarily reflect those of the FREE Network and its research institutes.