Collaborating in teams by using various digital information and communication technologies (ICTs) to perform interdependent tasks and achieve common goals relevant for one’s organization is increasingly the new normal. Such more or less virtual teams—which can be all human or human-agent teams (HATs) (i.e., including autonomous software agents with artificial intelligence)—are complex dynamic open socio-digital systems embedded in an organizational, economical, and societal context. How and to what degree team members use ICTs to perform their tasks and to manage situational demands influence team processes and emergent states, such as transactive memory systems and team mental models, and thus team effectiveness. Research on input-mediator-output-input models of teamwork has shown that these processes are reciprocal, influencing team development over time. Research on virtual team effectiveness shows negative effects of virtual teams on team functioning and effectiveness primarily when short-term laboratory teams are studied, whereas no or lower effects were found for long-term organizational teams. These results have practical and theoretical implications, such as to support the launch of virtual teams by team-building interventions and trainings and to prefer longitudinal and field studies to examine processes and outcomes of virtual human teams as well as HATs.