This chapter explores the dynamics of trust and mistrust within ethnic communities, particularly in the context of immigrant entrepreneurship. It introduces the concept of ‘bounded trust’, which describes the solidarity and mutual support that coethnic members foster within shared cultural and social boundaries. This trust often facilitates collective resilience and resource-sharing, essential for navigating the challenges of migration and entrepreneurship. However, the chapter also highlights ‘bounded mistrust’, where competition, cultural tensions, and divergent interests within the same ethnic group lead to fragmentation and even sabotage. Drawing from examples such as Brazilian immigrant entrepreneurs in Florida and Western Australia, the chapter demonstrates how social and cultural factors shape the interactions within ethnic communities. It examines how trust, solidarity, and reciprocity operate within specific contexts, such as Brazilian and Asian migrant networks, illustrating their reliance on cultural mechanisms like guanxi in Asian communities and shared ‘Brazilian work ethic’ traits. While trust fosters collaboration, mistrust—rooted in socioeconomic disparities, regional rivalries, or competition with informal businesses—often undermines community cohesion and entrepreneurial growth. The chapter also discusses generational shifts in trust dynamics and the influence of host-country environments on migrant networks, drawing parallels with historical and contemporary examples of ethnic enclaves. By examining the dual nature of trust and mistrust, this chapter deepens our understanding of ethnic entrepreneurship, community integration, and the socioeconomic challenges migrants face. It highlights the need for inclusive policies to support immigrant businesses, reduce barriers to formalisation, and promote equitable opportunities for coethnic and cross-cultural collaboration.