Interfaces, interactions, and time are commonly understood as foundational constructs in the field of organizational frontlines, but their current definitions are fragmented and disconnected. We propose a set of propositions drawn from theorizing the foundational constructs to facilitate systematic studies of frontline phenomena and promote integration across studies. We also advance the concept of the frontline nexus, a constellation of relations that interconnect the foundational constructs, and propose that the nexus is the appropriate unit of analysis for the study of organizational frontlines. To specify a system that embeds the frontline nexus and situates its foundational constructs, we discuss the role of agency, technology, learning, and privacy as key structural characteristics. In response to changing frontlines, we offer 11 propositions to advance research and practice of organizational frontlines. These propositions encourage researchers to explore the potential of new technologies, investigate the role of frontline actors in shaping interaction outcomes, examine the impact of learning and development initiatives, and consider the ethical implications of frontline actions.