The purpose of the present study was to examine associations between consensual non-monogamous and monogamous relationships and various aspects of the relationship, such as attachment, satisfaction, commitment, inclusion of other in self, and trust. Participants (N = 996) were solicited online and asked to rate a number of items regarding their type of relationship, attachment, satisfaction, commitment, inclusion of other in self, disclosure, trust, and demographics. Predictions were made that: (1) individuals in consensually non-monogamous and monogamous relationships would have significantly different levels of attachment; (2) individuals in consensually non-monogamous and monogamous relationships would rate satisfaction significantly different; (3) individuals in consensually non-monogamous and monogamous relationships would have significantly different levels of commitment to the relationship; (4) the open partners' willingness to disclose relationship status to the outgroup would be significantly correlated with self-other overlap; and (5) individuals in consensually non-monogamous and monogamous relationships would rate relationship trust significantly different. Hypothesis 1 was not supported, as individuals in open relationships were not significantly different in attachment from those in closed relationships. Hypothesis 2 was supported, as satisfaction was significantly higher for partners in a consensually non-monogamous relationship. Hypothesis 3 was not supported, as there was not a significant difference between individuals in open or closed relationships with respect to degree of relationship commitment. Hypothesis 4 was not supported, as participants in both open and closed relationships the association between self-other overlap and disclosure was nonsignificant. Hypothesis 5 was not supported, as there was not a significant difference between individuals in open or closed relationships with respect to degree of relationship commitment. The research findings are discussed in the context of minority stress theory, possible selves, study limitations, and areas for future research.