Building the Evidence Base for Intergroup Contact Theory: Introduction to Linda R. Tropp's Kurt Lewin Award Address

It all began in 1998 while Linda Tropp and I waited for a slow elevator in the psychology building at the University of California, Santa Cruz (UCSC). I mentioned to her that I was considering conducting a meta-analysis of intergroup contact studies, and I asked her if she would like to be involved. New contact studies were being reported, and meta-analytic procedures had sharply advanced. But the task seemed to me to be almost overwhelming in size and scope.

Still in the midst of her graduate training, Linda was immediately excited by the idea, and fortunately, she did not see it as overwhelming. To conduct the initial searches, she enlisted the aid of 16 outstanding undergraduate psychology majors at both UCSC and Boston College, where she later held her first faculty position.1 We had no research funding at that point, so we offered the students course credit for independent research focused on meta-analysis. The students uncovered more than 800 contact references, many of which needed to be translated from other languages. I managed to read the ones in Dutch, Afrikaans, and German; Linda was able to read those in Spanish, and we recruited four additional translators, including my Arabic-fluent son, Mark, for the rest of the non-English papers. I reviewed each of them and found 515 studies with 713 independent samples usable for our meta-analysis. And then I determined the effect sizes for each of the 515 relevant studies.

We thought our meta-analysis (Pettigrew and Tropp 2006) would attract greater attention to the intergroup contact literature. But we did not anticipate the flood of new studies and ideas on contact that soon flowed throughout social psychology. Indeed, over the years, we have been credited with sparking a “renaissance” in the study of intergroup contact. Thousands of contact papers followed the publication of our 2006 paper, and growth in this literature continues (see Paolini et al. 2021). In the International Journal of Intercultural Relations alone, three consecutive journal issues in 2024 and 2025 featured 14 articles on intergroup contact. And, according to Google Scholar, as of August 2025, our 2026 meta-analysis has been referenced more than 13,000 times. Tropp herself has contributed heavily to the deluge of publications on intergroup contact; all told so far, she has authored or coauthored 90 published or in-press papers on intergroup contact.

Moreover, various applied fields have found intergroup contact theory and research useful in practice, a core interest Linda and I have long shared and one that is exemplified by the Lewin Award. Some recent studies show that intergroup contact contributes to reducing prejudice even in the face of threat and amidst protracted conflict (Grady et al. 2023; Van Assche et al. 2023). To my mind, the most important applications of intergroup contact research involve multilevel analyses that include the macro-structural level of analysis (Pettigrew 1996 2006). Consistent with the theorizing of Emile Durkheim, these studies demonstrate how normative structures act as critical contextual variables shaping intergroup contact effects.

One major contact study analyzed with multilevel methods included seven large-scale European surveys (Christ et al. 2014). This research specifically tested for macro-level effects of positive intergroup contact in reducing prejudice within regions, districts, and neighborhoods. The authors found that these macro-level effects were larger than contact effects observed at the micro-individual level. And the significant macro-level effects were largely mediated by more tolerant norms supporting contact between groups. The authors stressed the importance of this macro-level process, as it can simultaneously impact large numbers of people, many of whom have not themselves had direct intergroup contact but who are influenced by the changed norms (see also Christ et al. 2010; Wright et al. 1997).

Later, a Swiss research team, using different data and methods, confirmed the finding that intergroup contact moderates the effects of social norms involving prejudice (Visintin et al. 2020). These authors concluded that intergroup contact is “a potent tool for reducing conformity to intolerant and anti-egalitarian norms” (p. 418). It is potent because such contact improves the norms surrounding intergroup relations, thereby enhancing both intergroup attitudes and intergroup behavior. Tropp has also been involved in testing contact processes in relation to a range of structural factors, to further build the contact evidence base and extend existing theory. For instance, with Luca Váradi and colleagues, Tropp has replicated and extended findings from Visintin et al. (2020), using longitudinal survey data to show that contact can buffer adolescents from adopting anti-Roma norms prevalent in the Hungarian context (Váradi et al. 2025). She has also recently collaborated with Judit Kende and colleagues on longitudinal multilevel analyses of probability surveys from non-migrants in nine North American and European countries (Kende et al. 2025). Extending prior work, their findings indicate that more inclusive immigration policies predict greater friendships with immigrants, and that greater friendships with immigrants improve non-migrants’ perceptions of immigrants. Importantly, they also find that exclusionary immigration policies predict poorer perceptions of immigrants, yet only among those who have few immigrant friends; when non-migrants report having greater numbers of friends who are immigrants, they maintain positive perceptions of immigrants irrespective of local policies. Together these lines of research both add empirical support for intergroup contact theory and critical extensions of the theory to the research literature.

Among my own awards, I regard receiving SPSSI's Lewin Memorial Award in 1987 as my most prized honor. So, it was a special delight to learn that, nearly four decades later, Linda Tropp has also won this same award. And she richly deserves it.

The author declares no conflicts of interest.