Family accommodation (FA) describes parents' attempts to help a child avoid feeling anxious by participating in symptom-driven behaviors and modifying family routines. FA is highly prevalent among parents of anxious children and has been linked to greater symptom severity in the child and to poorer response to ICBT. Research has linked a number of biological and behavioral parent markers to protective parental behavior and to child anxiety. The nonapeptide oxytocin (OT) is implicated in parental attachment and protective behavior in humans and animals. Coded behavioral observations link aspects of parental behavior (i.e., autonomy granting, over involvement, and sensitivity) to child anxiety. A number of studies also have shown that these biological and behavioral markers interact to predict anxiety outcomes in at-risk children. Yet so far this research has been siloed from intervention research and has not informed parent-based treatments, highlighting the need for clinical investigators equipped with the necessary skills to integrate multiple units of analysis into explanatory RCTs of novel interventions.