Broadly speaking, attachment theorists have argued that the unconscious, social–cognitive process of transference is one of the mechanisms underlying attachment stability and coherence. This study assessed the transference of friend and sibling attachments and examined differences between single and romantically coupled individuals. Attachment‐related feelings transferred to new individuals who resembled friends and siblings, and this process was especially true for single people. Having more siblings corresponded to greater attachment security for all participants, and larger friend networks buffered singles specifically from attachment insecurity. In general, friend and sibling relationships appeared to be more influential for single individuals, pointing to the importance of these significant others in singles' lives.