BACKGROUND: There is a lack of clarity regarding specific risk factors discriminating generalized anxiety disorder (GAD) from panic disorder (PD). GOAL: This study investigated whether GAD and PD could be discriminated through differences in developmental etiological factors including childhood parental loss/separation, psychological disorders, and maternal and paternal attachment. METHOD: Twenty people with adult generalized anxiety disorder (GAD), 20 with adult panic disorder (PD), 11 with adult comorbid GAD and PD, and 21 adult non-anxious controls completed diagnostic interviews to assess symptoms of mental disorders in adulthood and childhood. Participants also reported on parental attachment, loss and separation. RESULTS: Childhood diagnoses of GAD and PD differentiated clinical groups from controls as well as from each other, suggesting greater likelihood for homotypic over heterotypic continuity. Compared to controls, specific phobia was associated with all three clinical groups, and childhood depression, social phobia, and PTSD were uniquely associated with adult GAD. Both maternal and paternal attachment also differentiated clinical groups from controls. However, higher levels of subscales reflecting maternal insecure avoidant attachment (e.g., no memory of early childhood experiences and balancing/forgiving current state of mind) emerged as more predictive of GAD relative to PD. There were no group differences in parental loss or separation. CONCLUSIONS: These results support differentiation of GAD and PD based on developmental risk factors. Recommendations for future research and implications of the findings for understanding the etiology and symptomatology of GAD and PD are discussed.