The quality of the attachment relationship between children and their parents/caregivers has a profound impact on their overall well-being and future relationships. Previous research has emphasized the importance of caregiver sensitivity (e.g., responsive and nurturing care) in fostering secure attachment relationships. However, regular close contact, support of child exploration, and welcoming the child’s return may be equally significant for the development of a secure attachments. To explore this further, we have developed wearable devices called TotTags that measure the physical proximity between children and their caregivers in their everyday lives. In this project, we aim to examine how everyday caregiver–child interactions are associated with attachment security. By combining measures of caregiver and child physical proximity with caregiver sensitivity, we seek to determine the factors that are most influential in establishing secure attachment relationships. Additionally, this study offers valuable insights into the daily lives of families with young children, providing a deeper understanding of contact patterns within and across families. The findings from this project have the potential to advance knowledge in psychology and developmental science, as well as inform interventions and support efforts for children and families. Furthermore, the foundation knowledge can contribute to a workshop for first-time parents, providing them with essential knowledge about child development and caregiving behaviors to promote healthy relationships.<br/><br/>This research project aims to study the relationship between caregiver–child physical proximity and attachment security in the relationships between infants and their parents/caregivers. To achieve these goals, the research team employs a mixed-methods approach, combining naturalistic observations with laboratory-based assessments. Given the theorized importance of regular close contact, support of child exploration, and welcoming the child's return, the project utilizes wearable devices called TotTags to measure patterns of physical proximity, on a second-by-second level, between children and their caregivers in their everyday lives across one full week. The goals of this research project are to examine how everyday caregiver–child interactions are associated with attachment security and to explore the factors that characterize secure attachment relationships. Specifically, we test whether time in close physical proximity, compared to caregiver sensitivity, better explains attachment security within a given parent–child dyad, as well as the potential interaction of proximity and sensitivity. By collecting data from a diverse sample of families with young children, the study aims to provide valuable insights into the daily lives of these families and the patterns of contact within and across families. The outcomes of this research project have the potential to inform interventions and support efforts for children and families, contributing to the development of effective prevention and intervention strategies.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.