Objective: While interpersonal and institutional sources of (dis)trust among adults are relatively well-explored, the perspectives of younger individuals are not adequately represented in literature. This gap in knowledge is particularly pressing because values and attitudes are greatly formed during adolescence, and young people carry these sources of (dis)trust into adulthood, where they continue to shape the functioning of democratic societies (Tyler, 2015). It is therefore crucial to understand what sources inform young people's trust in institutions and society and whether these sources vary across young people and adults today. Method: To explore the importance of different sources of (dis)trust from childhood to adulthood we adopt a mixed-methods approach (Maxwell, 2022). As first step, we conducted a realist reflexive thematic analysis (Braun & Clarke, 2019) to identify, conceptualize, and connect various sources of (dis)trust. As a second step, we will conduct a vignette experiment to assess the combined effect of some of these sources and their importance across different age groups. The sample for the thematic analysis consists of 39 participants from the Czech Republic, divided into eight focus groups (collected in Summer 2022). The sample for the vignette experiment will consist of a large sample of approximately 3600 participants from the Czech Republic, Germany, Italy, and Serbia (will be collected in Spring 2023). Both samples are divided into four age groups: 11-12, 14-15, 18-19, and 30-50 years old. Results: Through a reflexive thematic analysis, we have constructed six overarching themes. In this contribution, we focus specifically on three of these themes that are most relevant to our subsequent vignette experiment: "The need for a predictable framework", "The quest for meaning - well-founded measures and well-acquainted people" and "Reciprocity." The first theme highlights that predictability is essential for trust, while unpredictability undermines it in both interpersonal and institutional contexts. The second theme emphasizes the meaningfulness of measures, restrictions and decisions as crucial for trust in government and policymakers. In the third theme we explore the reciprocity of trust in interpersonal relationships and its role in ensuring mutual trust. Lastly, while predictability, meaningfulness, and reciprocity were mentioned by all age groups, children and adolescents viewed the predictability and meaningfulness of measures adopted by authorities as less crucial compared to adults. Discussion: Our analysis suggested sources of (dis)trust referring to the processes through which trust and distrust may grow or deteriorate. We posit that these attributes may also be related to the fulfilment of basic needs in the epistemic (certainty), existential (security), and relational (meaningful relationships) domains, as proposed by the system justification theory (Jost, 2019). Additionally, the findings that predictability and meaningfulness were considered less crucial by younger age groups (in relation to trust in authority) may be partly attributed to the different effects of the authorities' decisions on adults, who experienced them more directly and in more aspects of their lives compared to younger individuals (Prime et al., 2020). Finally, our upcoming vignette experiment will provide additional insights into the combined effects and relative importance of the sources of (dis)trust for different age groups.