The United States has suffered a major measles epidemic and the National Vaccine Advisory Committee has predicted that the epidemic will be followed by outbreaks of other vaccine-preventable diseases. The primary cause of the measles epidemic was failure to immunize preschool-aged children. Unless major changes are made, the Objectives in Healthy People 2000 for vaccine-preventable diseases, which include zero measles cases, will not be achieved. The multiple causes of the low immunization rates include high cost, the number of injections, lack of access to providers, and barriers within the health delivery system. The available data about these issues are limited, have not been obtained in a systematic fashion, and generally do not include information about hepatitis B and Haemophilus influenzae type b conjugate vaccines. This project will evaluate seven immunization barriers as they relate to primary care physicians, who provide the majority of childhood immunizations in most areas. Their knowledge, attitudes, and practices will be quantified about the following: 1) their practices and rationale for or against simultaneous administration of multiple injections, 2) their understanding of indications and contraindications in clinical situations, 3) their knowledge and beliefs about vaccine safety and disease communicability, 4) their concerns about vaccine litigation, 5) their attitudes and practices about vaccine reimbursement, including differential referral to public vaccine clinics based upon insurance status and participation in the new federal vaccine distribution system, 6) their use of office procedures that facilitate immunization, such as a team approach, and 7) the impact of the lengthy Vaccine Information Pamphlets which can lead to less compliance with immunization and prolongation of office visits. Subjects will come from a national, random sample of primary care physicians that is selected by specialty (family physicians, general practitioners, and pediatricians). These physicians will be interviewed by telephone about immunization barriers in their practices. According to Healthy People 2000, surveys of primary care providers about preventive services are a "high priority need." Patient charts will be reviewed to assess simultaneous administration of multiple vaccines, interpretation of contraindications, and the use of a team approach. The chart reviews will provide additional validity data. The project will furnish data in order to enhance public policy planning and medical education. In particular, officials need to know the relative importance of various barriers, geographic variation in immunization barriers, and characteristics of providers who would most benefit from educational intervention. The measles epidemic underscores the need for data upon which to base public policy so that children in the United States do not continue to die needlessly from preventable diseases.