Most members of Congress begin their careers through regularly scheduled elections, but terms may be cut short due to death, scandal, or different career opportunities. In these cases, special elections are held to fill vacancies. In fact, a number of prominent political figures, including Lyndon Johnson, Nancy Pelosi, and John Dingell, began their long and distinguished careers through special election to Congress. While the media often look to special elections as a way of measuring public sentiment on presidential performance, even though voter turnout tends to be significantly lower than in regular elections, these events have rarely attracted academic attention. Oftentimes, studies of these contests lead to generalizations about how a party should proceed if it hopes to wrest a seat away from the opposition in a special election. This book is the first large-scale scholarly treatment of special elections: both in terms of explaining what factors influence outcomes and in determining whether special elections are bellwethers for general elections. Charles S. Bullock, III and Karen L. Owen argue that special elections offer parties a testing ground for messaging and strategies for mobilizing voters in anticipation of general elections. Moreover, these elections provide opportunities for diversification of Congress as reduced commitment to resources for campaigning has led more women and candidates of color to compete in them-and win. Based on 75 years of data, the authors closely examine several competitive special elections during the first two years of the Trump era and quantitatively assess the almost 300 House special elections held since World War II.