limits) as well as their satisfaction in regards to health care. This definition leaves more opportunities for individual interpretation as compared to that of the economical and structural underinsurance definitions. The attitudinal underinsurance definition is recognized when; (1) at least one health benefit that the individual would prefer to receive is not covered by insurance, (2) when there is at least one symptom that the person believed required treatment for which insurance coverage treatment was not provided, or (3) when a person is dissatisfied with their insurance plan. Because there adequate room for personal interpretation in this definition, surveys that are conducted using this definition often are not always as well accepted when compared to surveys that are conducted using the structural and economical definitions. Structural Underinsurance Structural definitions of insurance, generally consider both the type of benefits that are offered by the healthcare insurance program, as well as the number and range of providers whose services are covered under the identified plan. A structural approach to defining underinsurance uses a benchmark benefits package as a basis of comparison. Structural underinsurance is utilized when at least one benefit in the benchmark package is not covered by the individual's health insurance plan. At risk populations and situations Children with Special Health Care Needs Children with Special Healthcare Needs (CSHCN) have been the most highly research population that experiences the effects of underinsurance. CSHCN have been routinely been defined as those who have or are at increased risk for a chronic physical, developmental, behavioral, or emotional condition and who also require health and related services of a type or amount beyond that required by children generally. All children who have been identified as CSHCN must be considered and taken into account when research is being conducted to further identify who is at risk for experiencing underinsurance. Vaccinations The number of vaccines that are recommended for children under 5 years old living in the United States experienced a significant increase, nearly doubling in the past ten years. With these recommendations and requests for further vaccinations, the cost for vaccinating a child has become increasing expensive. The differences in health insurance coverage (private vs. public), along with the current vaccine financing system that is in place, together have combined to result in significant gaps in vaccination coverage and distribution for children in the U.S. These gaps then translate into children being underinsured and not