The purpose of this study is to investigate attitudes concerning the Measles, Mumps, & Rubella (MMR) vaccine among adult parents in the United States. Attitudes will be assessed via a web-based survey administered by Survey Sampling International (SSI). Project sample size is 1,000, all to be recruited by SSI. The survey will take no more than 20-30 minutes to complete. The survey questions and response options attached. With the exception of demographic questions (e.g., age, sex, race) at the end of the survey, questions will not be able to be "skipped" because 1) the survey questions primarily assess attitudes and beliefs, 2) the questions are not of a sensitive nature, 3) responses are anonymous, 4) respondents have indicated their desire and willingness to respond to surveys like this by virtue of their enrollment as an SSI panel member, 5) there is no pressure for respondents to complete the survey, 6) respondents may cease responding to the survey at any time after they begin.