A direct test of the belongingness hypothesis: how fully vs. partially satisfying relationships relate to perceived belongingness and well-being.

Introduction: Vital components of the "belongingness hypothesis" set forth by Baumeister and Leary were examined: (a) fully satisfying relationships-referred to here as "whole" relationships-are defined by a set of criteria, and some small number of these relationships are required to meet one's belongingness needs; (b) relationships that do not meet these criteria do not predict belongingness and well-being as do whole relationships; and (c) the satisfaction of maintaining additional relationships beyond the minimum number is diminished. The present research examined whether the benefits of interpersonal relationships diminish as the number of whole relationships increases. Methods: Collegiate samples ( Results and discussion: Fully satisfying relationships specifically classified by a set of criteria were positively related to belongingness and well-being. In contrast, increasing numbers of interpersonal relationships that failed the criteria for a whole relationship were not positively related to belongingness, but instead were negatively related. Finally, although whole relationships showed linear associations with belongingness and subjective well-being, significant quadratic effects were also found in two of three studies. That is, gains in belongingness and well-being showed evidence of gradually diminishing as the number of whole relationships extended beyond minimum requirements. The results support the utility of distinguishing between whole and partial relationships as originally theorized.