Cooperative communal relationships in which people attend to one another’s welfare and act so in ways that ensure and promote partner welfare, non-contingently, are defined and discussed. They are both qualitatively distinct from other types of cooperative relationships, such as those which are transactional in nature, and from non-cooperative relationships, such as exploitative ones. Communal relationships vary in strength. This means that people assume different degrees of responsibility for their different communal partners and have a good sense of the extent to which they will expend time, effort, and money to benefit their partner non-contingently. Communal relationships are often (but not always) exemplified by the relationships we have with family, friends, and romantic partners, yet even relationships with acquaintances can be weak communal relationships. In general, communal relationships promote their members’ sense of security, belongingness, and well-being.