The types of interactions that we believe to be most supportive of positive child development (e.g., joint attention, physical touch) take place in moments of close contact with others, and in the earliest years of life a child’s caregivers are the primary partners in these important interactions. However, we know little about the patterns of real-life interactions between children and their caregivers. To address this gap, we have developed a wearable, infrastructure-free device (TotTag) used to dynamically and unobtrusively measure real-time physical proximity between children and caregivers throughout the day. The present study examines the TotTag validity and reliability with data collected over two days from a family of four (30-month-old son, 61-month-old daughter, 37-year-old father, 37-year-old mother), including information about their patterns of interaction as well as how the children’s experiences might differ depending on proximity to their caregivers. We explored patterns of proximity across the day within each parent–child dyad and whether measurements corresponding to close proximity between child and caregiver would indicate periods in which increased opportunity for developmentally critical interactions occur. Each child also wore a widely-used wearable audio recording device (LENA) to collect time-synced linguistic input. Descriptive analysis of the TotTag data reveal wide variability in caregiver–child proximity over the course of the recordings. Further, results suggest that the amount of time spent in close proximity with a caregiver is associated with the quantity of a child’s exposure to adult language, suggesting that variations in proximity are linked to, though not synonymous with, the experience of adult speech. Potential implications for deepening understanding of early caregiver–child interactions are discussed.