Vacancy

•       MA/MSc degree in demography or related discipline; interest in, and ideally some familiarity with sociology
•     Interest in the topic of social cohesion and in collaborating in a broad research consortium with academic and non-academic stakeholders
•     Strong interest in interdisciplinary research, including analytical and theoretical dimensions
•     Professional competence in English 
•     Competence in Dutch is a plus 
•     Interest and skills in quantitative and statistical methods
•     Interest in the topics of migration and migrant integration
• We look for team players who want to play an active role in an inter- and transdisciplinary research community and training programme

This PhD project investigates how social cohesion develops among adolescents who attend ethnically diverse secondary schools. It traces how different cohesion dimensions, such as interethnic friendships, school attachment, trust in institutions and national identity, co-evolve. The project seeks to develop and test a multidimensional framework of social cohesion in the context of increasing ethnic diversity. In particular, the project seeks to uncover how dimensions along horizontal lines of cohesion (i.e., relationships between individuals and groups, such as friendships, intergroup attitudes and social rejection) connect to vertical lines of cohesion (i.e., ties between individuals and institutions, such as trust in the government, feelings of national belonging and school attachment) among youth. To this end, the project will analyse diverse school contexts and identify how school- and regional-level conditions strengthen or weaken these horizontal and vertical cohesion dimensions as well as the association between these two dimensions. It further aims to design and test an intervention that fosters positive spillovers between both dimensions and project how cohesion may evolve under changing demographic scenarios. Ultimately, the project aims to generate new theory, robust empirical insights and practical tools that help educators and policymakers strengthen cohesion among youth in a sustainable way.

Rationale and Research Question

Social cohesion is essential for the stability of modern societies, but despite decades of research, our understanding of cohesion remains fragmented. This PhD project aims to move the social sciences beyond such fragmentation by focusing on a ‘microcosmos’ of society: secondary schools. It advances current understanding by developing and empirically testing a dynamic model of social cohesion that captures the interplay between horizontal cohesion (i.e., connections between individuals and groups, such as friendships, intergroup attitudes and loneliness) and vertical cohesion (i.e., ties between individuals and institutions, such as trust in the government, feelings of national belonging and school attachment). By investigating when and why these dimensions reinforce or counteract one another, the project offers a new theoretical lens on social cohesion.

The project focuses on adolescents aged around 14 to 18 and the schools they attend. Schools are an ideal context for studying the broader dynamics of social cohesion. They are among the first social institutions in which young people from different ethnic, social and socio-economic backgrounds interact daily. Within this setting, a wide range of cohesion-relevant processes unfold simultaneously: friendship formation and exclusion, experiences of loneliness and belonging, encounters with authority and the development of trust in institutions and society more broadly.

The project thus uses schools as a lens to understand how horizontal relations between peers and vertical relations to institutions become intertwined during a formative life stage, when attitudes, identities and expectations begin to crystallize and can carry over into adulthood. In this sense, schools provide a uniquely rich and flexible research environment for studying the foundations of social cohesion and segregation while allowing findings to speak to wider societal processes beyond the school context itself.

Scope of the Project

The scope of the project is both empirical and theoretical. It seeks to test and refine the core SOCION proposition that social ties at different levels are interconnected and can either strengthen or weaken one another. The project will proceed in four main steps. First, it will map how horizontal and vertical ties are related across ethnically diverse schools, using large-scale survey data. This will provide a systematic overview of how the two dimensions of cohesion align or diverge across settings. Second, it will explain why these relationships differ by examining school characteristics and regional characteristics, such as ethnic and socio-economic diversity, tracking systems and school policies. Third, it will translate these insights into practice by co-developing and testing an intervention designed to foster positive spillovers between horizontal and vertical cohesion. Finally, it will extend the findings to broader socio-demographic trends through scenario modelling, which explores how demographic change or ethnic segregation might affect the interdependence of cohesion’s dimensions in the future.

Project Deliverables

In doing so, the project will deliver several key outputs: 

• It will develop a theoretical framework that conceptualizes social cohesion as a system of interrelated dimensions rather than as separate outcomes. 
• It will generate novel empirical evidence on how these dimensions interact across diverse school contexts, using statistical modelling techniques such as multilevel modelling and social network analysis.
• Through the intervention study, it will also produce practical insights and data-driven recommendations for educators and policymakers on how to effectively strengthen social cohesion, avoiding the unintended consequence of improving one aspect while undermining another.
• Finally, by connecting microlevel dynamics with macrolevel scenarios, the project will contribute to evidence-based foresight on the future of cohesion under changing demographic conditions.

Connection to Social Cohesion

This PhD contributes directly to SOCION’s central research agenda, investigating the mechanisms that bind societies together and asking how connections between individuals, groups and institutions can be strengthened without unravelling them elsewhere. It complements other projects by focusing on the formative phase of adolescence and the institutional context of schools. While other SOCION projects emphasize, among other things, adult populations or neighbourhood-level interactions, this project situates cohesion in the social world of youth, where habits of trust, belonging and engagement first take shape.

This project draws on large-scale secondary survey datasets that capture the horizontal and vertical dimensions of social cohesion among youth in ethnically diverse school contexts. These data provide rich and partly longitudinal and cross-national information that enables us to examine how the horizontal and vertical dimensions of cohesion co-occur within and across schools.

The first dataset is the Children of Immigrants Longitudinal Survey in Four European Countries (CILS4EU), including approximately 18,000 adolescents from around 800 classrooms nested in 400 schools across Germany, the Netherlands, Sweden and England (2010–2017). The second is the Educational Monitoring Study (2022) conducted by the Institute for Educational Quality Improvement (IQB) at Humboldt University of Berlin, with around 1,300 classrooms of students across Germany. Both datasets contain extensive measures of horizontal ties (e.g., friendships, interethnic attitudes and networks) and vertical ties (e.g., school attachment, national belonging and trust in institutions), and they complement each other in terms of period, scope and measurement.

The analytical design follows the four steps of this project, applying different statistical techniques (multilevel modelling, meta-regression, social network analysis). First, it will examine the extent to which horizontal and vertical cohesion are related and assess the degree of heterogeneity across schools (step 1). Second, it will explain this variation by testing the role of factors such as school composition, diversity policies and broader contextual characteristics (step 2). Based on these insights, and in collaboration with stakeholders, the project will design and pilot school interventions aimed at strengthening cohesion, collecting experimental data in one to two schools to evaluate their impact (step 3). Finally, the project will integrate findings from the first three steps into simulation models that project how horizontal and vertical cohesion may evolve under different demographic and policy scenarios, such as increasing ethnic diversity or school segregation, based on simulation methods (step 4).

Lorenz, G., & Rjosk, C. (2025). Fragmentation or integration? Ethnic diversity and the structural cohesion of adolescent social networks. European Sociological Review. Advance online publication. https://doi.org/10.1093/esr/jcaf051

Smith, S., Maas, I., & Van Tubergen, F. (2014). Ethnic ingroup friendships in schools: Testing the by-product hypothesis in England, Germany, the Netherlands and Sweden. Social Networks, 39, 33–45.