This dissertation focuses on the emergence and evolution of social networks by paying particular attention to the spanning of cultural boundaries that segregate actors in the context of specific societies. In particular, I use systems science methods to study the bridging of cultural holes in small and relatively dense artificial societies, as well as in an American high school. I also study the significance of local triadic configurations in giving rise to the highly hierarchical system of aggregate-level migration flows in place in the Americas during the late 20th century. I use the concept of liminality as a way to analyze these disparate social systems. More precisely, I focus on the role of cultural brokers seen as actors at the limen – i.e. at the border – of symbolic boundaries, actors that can act as bridges between culturally disconnected worlds. In this context, this dissertation explains key network dynamics behind two emergent phenomena that are the direct result of liminal agents’ behaviors: the diffusion of innovations (Chapters 1 and 2) and a system of international migration flows (Chapter 3). Finally, I also put forward a critical view on brokerage based on different cases mentioned in the literature (e.g. 1.5 generation migrants or multiracial individuals) that show how the spanning of cultural holes can put brokers at an increased risk of being socially and/or psychologically harmed.