The investigators would like to understand how the physical activity levels and body size of a child with cerebral palsy (CP) in a clinical situations versus out in the community relates to what they want to do in day to day life (participation in life). The investigators believe that what a child really does out in day to day life will predict life participation to a greater degree than what they do in a structured clinical situation (i.e. therapy session with therapist). The investigators think that increased body size with normal growth is related to less physical activity and participation in day to day life for children with cerebral palsy (CP) who can walk. This project will use a novel accelerometer to measure walking activity during day to day life.

We want to know how the physical activity of children with walking problems or cerebral palsy (CP) relates to what they do in their day to day lives.

We are looking for children who:

• Have walking problems that started before age 2
• Have any type of cerebral palsy (CP) or primary problem that is a developmental movement disorder
• May have hemiplegia, diplegia, walking quadriplegia, May have ataxia, spastic, mixed tone, athetoid, or dyskinetic
• Ages 2 years to less than 10 years
• Able to do some functional walking with or without help(walkers, gait trainers)
• Project requires a one time visit to Seattle Children's Hospital of about 2 hours.
• Children and/or parents will complete surveys.
• The child will be tested for their gross motor and walking skills like at a physical therapy session.
• The child will be given an ankle monitor to wear for 7-10 days.
• They will return the monitor by mail with a questionnaire about what they did the last week.
• Families will receive a print out of their child's walking activity

Inclusion Criteria:

1. age 2 to <10 years (30 per four age groups/2 year increments)
2. Gross Motor Function Classification System (GMFCS) levels I-III
3. diagnosis of cerebral palsy (CP) or developmental movement disorder that occurred prior to age two.

Exclusion Criteria:

1. visual impairment limiting physical activity
2. lower extremity botox injections in the last 3 months
3. uncontrolled seizure disorder impacting mobility skills
4. orthopedic or neurosurgery in the last 6 months.

Children with cerebral palsy (CP) or developmental movement disorder before age two who are able to walk