Four topics—risk perception measurement; how risk perception shapes outcomes such as behavioral intentions and policy support; and sources of risk perceptions—usually are studied separately, despite obvious mutual implications: e.g., whether and how risk perceptions are affected by, or affect, other variables might depend on how they are measured. This project will put them in a rare longitudinal panel survey design and with standardized hypothesized predictors and outcomes, to maximize the ability to make causal inferences relative to more usual cross-sectional designs, preceded by systematic testing of alternative risk perception measures to draw conclusions about the relative value of alternative types and phrasing.