Inclusion Criteria:  Ages between 8 and 18 years old, inclusive. Diagnosis of CP and a pathological gait pattern caused by ankle dysfunction. Able to understand and follow simple directions (based on parent report, if needed) and walk at least 30 feet with or without a walking aid (Gross Motor Function Classification System (GMFCS) Level I-III). At least 20° of passive plantar-flexion range of motion.  Exclusion Criteria:  Concurrent treatment other than those assigned during the study. A condition other than CP that would affect safe participation. Surgical intervention within 6 months of participation.