Parent–child synchrony, or the coordination of biological and behavioral processes between parent and child, is thought to promote healthy relationships and support youth adjustment. Although extensive work has been conducted on parent–child synchrony during infancy and early childhood, less is known about synchrony in middle childhood and adolescence and the contextual factors that impact synchrony, particularly physiological synchrony. This is a systematic and qualitative review of 37 studies of behavioral and physiological synchrony in parent–child interactions after early childhood (parents with youth ages 5–18). Behavioral and physiological synchrony were typically identified in youth and their parents beyond early childhood and related to positive outcomes; however, research on father-child synchrony is rarer with mixed findings. Multiple factors are associated with synchrony, including parent and youth psychological symptoms and disorders, parenting factors, such as over-controlling parenting, and parent characteristics, such as interparental aggression and conflict. Few studies have examined behavioral and physiological synchrony simultaneously and longitudinally, limiting our ability to understand the relationship between types of synchrony and later adjustment. Available studies suggest that the context, such as presence of psychopathology or exposure to trauma, influences whether synchrony is associated with positive or negative outcomes. This review highlights the need for additional research to understand the relationship between types of synchrony and the long-term effects and contextual factors that impact youth outcomes.