 The extent of bone mass built up during childhood and adolescence is the most important determinant of osteoporosis later in life. Some disabled children, such as those with cerebral palsy, are particularly vulnerable to low bone mass accumulation due to decreased mobility and weight-bearing. These children also have poor muscle strength and control, which limits function and contributes to the lack of mechanical stimulation needed to build bone mass. The most common treatment for these children is physical therapy, which is time- and labor-intensive and may not be adequately available to them. Whole body vibration has shown promise as an alternative method for stimulating increases in bone mass and improvements in muscle. The purpose of this study is to evaluate the effects of high frequency, low magnitude vibration on bone and muscle in children with cerebral palsy. This intervention may be useful as a noninvasive, nonpharmacological treatment for low bone mass and poor muscle function in these children. 