Why do public issues like the environment rise and fall in importance over time? To what extent can the trends in salience be explained by realworld factors? To what degree are they the product of interactions between media content, public opinion, and policymaking? This book surveys the development of eight issues in Canada over a decade - AIDS, crime, the debt/deficit, the environment, inflation, national unity, taxes, and unemployment - to explore how the salience of issues changes over time, and to examine why these changes are important to our understanding of everyday politics.