This report summarizes an outbreak of measles among five unvaccinated children living in a U.S. military community in Wiesbaden, Germany, in March to April of 2004. The index case was a 3-year-old whose parents' refusal to have their child vaccinated with measles-containing vaccine had been documented many times. Four other cases developed from contact with the index case. The two older children had multiple missed opportunities for vaccination documented. Record review revealed that only 71% of 19- to 35-month olds in the community had been vaccinated with measles-containing vaccine before the outbreak, creating a "pocket of susceptibility." Children of travelers, expatriates, and military service members are at increased risk from vaccine-preventable diseases. Vaccine refusal is increasingly common, resulting in pockets of susceptibility to vaccine-preventable diseases, and increasing the risk of outbreaks. Missed opportunities and other delays in vaccination can also contribute to these pockets of susceptibility.