Dyadic Strengths-based Appreciation Intervention for Siblings: Improving Relationship Quality and Well-being

Adult sibling relationships—often the longest-lasting family bonds—are a central component of relational life, yet they remain largely overlooked in intervention research. This study tested a dyadic program designed to enhance adult sibling relationship quality and mental well-being through behavior-based appreciation of sibling-identified character strengths. Seventy-nine adult sibling pairs were randomly assigned to one of three conditions: (1) strengths-based appreciation— prior to the first session, each sibling named three character strengths from the VIA classification—a widely used framework of 24 character strengths—that best described their sibling based on personal knowledge, shared them with their sibling and then, across six weekly 20-minute sessions, recalled and shared specific behavioral examples from the past week that expressed these strengths, and expressed appreciation for them; (2) active comparison group—six weekly 20-minute sessions in which siblings shared three positive dyadic interactions from the past week and expressed appreciation for them; and (3) no-treatment control. Relationship quality and personal well-being were measured at baseline, post-intervention, and one-month follow-up. Only the strengths-based appreciation group showed a significant and large effect size increase in sibling relationship quality from baseline to post-intervention, and a significant increase in mental well-being from post-intervention to the one-month follow-up. Qualitative analysis of 860 appreciated strength-based behaviors indicated that they were most often expressed in work or study contexts and distributed across multiple life domains, as observed by siblings, whereas the 717 reported interactions in the active comparison group were exclusively dyadic and centered on sibling interactions. These findings suggest that strengths-based appreciation may broaden perspectives, shifting from viewing a sibling primarily within the relationship context to recognizing their capabilities across multiple life domains. This mixed-methods study highlights the potential of dyadic strengths appreciation as a brief intervention to strengthen adult sibling bonds and enhance personal well-being.