Matt A. Barreto is Professor of Political Science and Chicana/o Studies at UCLA and the faculty director of the UCLA Voting Rights Project. His research and teaching focuses on voting rights, expert witness reports and social science methodology.

Matt received his Ph.D. in political science from the University of California, Irvine in 2005, and had been on the faculty at the University of Washington for 10 years before joining UCLA in 2015. He has published three books, and more than 70 peer review journal articles, and is one of the leading scholars and pollsters on Latino public opinion and voting patterns. In 2016 Barreto was hired by the Clinton presidential campaign to manage polling and focus group research among Latinos, and in 2020 he joined the Biden presidential campaign to oversee Latino messaging research.

He is the author of the book, Ethnic Cues: The role of shared ethnicity in Latino political behavior published by the University of Michigan Press in 2010. In 2013 Barreto co-authored a book with Christopher Parker, Change They Can't Believe In: the Tea Party and Reactionary Politics in America, with Princeton University Press, which was awarded the American Political Science Association Best Book Ward for Race, Ethnicity Politics in 2014. In 2014 he co-authored the book Latino America: How America's Most Dynamic Population is Poised to Transform the Politics of the Nation with Gary Segura, which was featured on MSNBC's Morning Joe and NPR's The Brian Lehrer Show in 2014.

In addition to his research on Latino voting patterns, Prof. Barreto has conducted extensive research on voting rights, and has been an expert witness in numerous Voting Rights Act lawsuits. In 2018, he co-founded the UCLA Voting Rights Project, with attorney Chad Dunn, which is one of the premier national institutes that focuses on legal training and expert research on voting rights, with courses in the Law School, School of Public Affairs, and Social Sciences. In 2019 Barreto was a key expert witness in three federal lawsuits challenging the U.S. Census Bureau inclusion of a citizenship question on the 2020 U.S. Census, providing testimony in three federal trials and assisting the New York and California Attorneys General in blocking the Trump administration from adding a citizenship question to the Census.  He also served as an expert witness in the 2012 Pennsylvania voter identification lawsuit Applewhite v. Commonwealth of Pennsylvania, where his research with Prof. Gabriel Sanchez proved crucial to the voter ID law being blocked. Barreto and Sanchez also provided an expert report in a lawsuit challenging the impact of the Wisconsin voter ID law on minority voters, and in 2012 the Wisconsin law was also put on hold. In 2014 Barreto and Sanchez teamed up again to provide an expert report and testify in Veasey v. Perry in a challenge to the Texas voter ID law, and a Federal Court struck down the Texas ID law as unconstitutional, in part basing her decision on the evidence presented by Barreto and Sanchez. In 2016-17, Barreto and Sanchez implemented research and an expert report challenging the voter ID law in North Dakota finding the law would prevent thousands of Native Americans from casting a ballot. A Federal Court blocked the North Dakota ID law twice. Most recently, they offered an expert report challenging the voter ID law in North Carolina which a federal court struck down in December 2019.

In 2011, Prof. Barreto was retained as the lead expert consultant for the State of California’s Citizen Redistricting Commission, and was specifically asked to advise the Commission on Section 2 and Section 5 of the Federal Voting Rights Act and conduct research on polarized voting and vote dilution. In 2012, he was qualified as an expert witness in Rodriguez v. Harris County, a Section 2 voting rights lawsuit regarding County Commission redistricting, where he provided a report and testimony on vote dilution and racially polarized voting with respect to Latino candidates. Barreto has testified dozens of times in federal and state court about vote dilution and racially polarized voting in a variety of cases. In 2020 Barreto worked with Prof. Loren Collingwood to provide expert research on vote dilution in East Ramapo Central School District.  In the lawsuit they used their eiCompare software package to implement surname matching and geocoding of the voter rolls, called Bayesian Improved Surname Geocoding (BISG), to more accurately identify the racial/ethnic demographics of voters.  Ultimately the court ruled that Barreto and Collingwood had correctly applied BISG and more precisely estimated vote dilution, ruling in favor of the NAACP and NYCLU plaintiffs.  It was the first ever application of BISG in a voting rights trial, a technique that had previously been widely used in published social science. He continues to actively research voting rights in Black, Latino, Asian American and immigrant communities.