The greater asymmetry observed in children with BPP is due in part to weakness of the impaired shoulder as well as to greater strength in the unaffected shoulder, revealing some compensatory mechanisms. Regarding the impaired shoulder of children with BPP compared with children with TD, significant strength imbalances occurred in flexion–extension and internal rotation–external rotation strength ratios. Finally, impaired shoulder strength in the group with BPP correlated with active range of motion.