More than one million children in the U.S.today are homeless. As a result, many of them lack regular health care. Ten years ago, a pediatrician in Phoenix, Arizona became the first to run his hospital’s mobile medical clinic – a doctor’s office on wheels. His goal was to help homeless children get the medical attention they need. Their problems –from sexually transmitted diseases to infections from living outdoors – are often very different than those of other children. The converted Winnebago known as “Big Blue” has now served almost 7,000 children. Health care challenges facing homeless children in America.