The purpose of the study is to see if manipulation of the neck will change the way people who may or may not have neck pain, walk under differing conditions.

Volunteers in this study will be asked to do the following: 1) complete a series of questionnaires about health status and undergo physical screening of neck to make sure that manipulation will not be harmful; 2) walk in socks or bare feet across a computerized mat under 3 conditions - normal walking pace, walking while looking up and down repeatedly; and walking while looking left and right repeatedly; 3) have one of 2 manual therapy interventions to the neck; 4) repeat the walking across the computerized mat under those same 3 conditions.

The 2 randomly assigned interventions are: cervical manipulation, or cervical contact. If assigned the manipulation, volunteers will lie face up and the trained therapist will move the joints in the neck in a gentle, but short and sharp manner which may produce a slight 'pop' or 'click'. If volunteers are assigned the cervical contact, they will lie on their back and the trained therapist will gently hold the head and neck for 45 to 60 seconds as they quietly relax.

Inclusion Criteria:

1. Volunteers may or may not have mechanical neck pain
2. Aged 18 to 70 years
3. If neck pain is present, must have Neck Disability Index score of at least 10 out of 50 points

Exclusion Criteria:

1. 'Red flag' items indicated in Neck Medical Screening Questionnaire such as history of a tumor, bone fracture, metabolic diseases, Rheumatoid Arthritis, osteoporosis, severe atherosclerosis, prolonged history of steroid use, etc.
2. History of neck whiplash injury
3. Diagnosis from physician of cervical spinal stenosis (narrowing of spinal canal) or presence of symptoms (pain, pins and needles, numbness) down both arms
4. Presence of central nervous system involvement such as exaggerated reflexes, changes in sensation in the hands, muscle wasting in the hands, impaired sensation of the face, altered taste, and presence of abnormal reflexes
5. Evidence of neurological signs consistent with nerve root entrapment (pinched nerve in the neck)
6. Prior surgery to neck or upper back
7. A medical condition which may influence assessment of pain or pressure pain thresholds (i.e. taking analgesics, sedatives, history of substance abuse, or cognitive deficiency)
8. Diagnosis from your physician of fibromyalgia syndrome
9. Currently pregnant, or could be pregnant