Respondents will be asked to provide information about their children's ages and sex, as well as historical recall information about their past vaccine decisions for their child/children. All respondents will receive general information from the Centers for Disease Control and Prevention (CDC) regarding MMR and the MMR vaccine (taken from the CDC's Vaccine Information Sheet), followed by summarized information about MMR and the MMR vaccine. A quarter of respondents will receive only this information. The other three-quarters of respondents will also receive additional "benefit" information that either underscores: a) the MMR vaccine's benefit to the child who receives it, b) the MMR vaccine's benefits to society as a whole, or c) the MMR vaccine's benefit to both the child who receives it as well as to society as a whole. The purpose of this additional "benefit" information (which will randomly vary among respondents) is to compare people's attitudes when they're given this information about the MMR vaccine's benefit to people's attitudes when they receive the general information. This information is noted in the attached survey, and mimics the information that parents are typically given in clinic settings regarding MMR and the MMR vaccine. The purpose of this study is to systematically assess people's responses to this information, which is already offered in clinical settings and is publicly available via the CDC.