In considering the realities of 21st century society, research cannot overlook how livelihoods are becoming increasingly defined by one’s (in)ability for and agency over movement, i.e. mobility, especially on the transnational scale. Simultaneously, the relational turn of public relations scholarship has emphasized a network perspective, examining how a set of relations among social actors—be it people, groups, or organizations—create systems that comprise, maintain, and/or disrupt society (Yang & Taylor, 2015). As such, public relations should be inclusive of the depth of multiple, rich, and mobile relationships in social networks that span national borders. Yet the development of the network perspective in public relations has not been without its limitations, notably the absence of public perspectives, actions, and realities—all of which impact the communicative interactions that produce their social networks. This research thereby incorporates a public perspective through insights from people who migrate to highlight an increasingly important dimension to public formation and relationship dynamics: mobility. In doing so, this dissertation takes an innovative qualitative approach to social network analysis (SNA), which integrates a visual network mapping exercise alongside qualitative interviews and ethnographic observations. Findings captured how the enactment and context of mobility impact migrant network dynamics across the world as well as their subsequent communication behaviors and relational expectations, particularly with U.S. civil society organizations (CSOs). They further depicted an organizational perspective that highlighted three dichotomies to how CSOs perceive and maintain their social networks, and showcased the role of mobility as an underlying context generating distinct actors, ties, and positioning. Findings lastly emphasized entanglements between social and other forms of capital as well as patterns in who is perceived as having versus needing capital.As such, this dissertation proposes the conceptualization of the mobile social network ecology, a concept that integrates social network analysis and the experiences of public mobility by accounting for distinct publics and organizations perceptions. It allows for public relations to better consider the impacts of the enactment and context of mobility on key public relationships, inclusive of the distinct publics of the modern world, the CSOs that seek to serve them, and their linkages to civil societies on a transnational scale. Additionally, in noting the significant ties between migrant publics and migrant-serving CSOs, this dissertation connects the exchanges of (social) capital within a mobile social network ecology to relational power dynamics and differentials, emphasizing their lived, embodied impact as well as introducing a new salient category: spatial capital. All together, these contributions advance public relations in reckoning with the transnational, globalized dimensions of the modern world, showcasing how public mobility shapes and complicates our fundamental societal connections and presenting unique takeaways for the field in scholarship and practice.