William G. Mayer is assistant professor of political science at Northeastern University.

• Forthcoming Titles -- Foreword -- Introduction: Party Unity and Presidential Elections -- Do Democratic Rules Make the Nomination Process More Divisive? -- The Divisive Primary Revisited -- Ideological Cohesion in the American Party System -- Ideological Cohesion over Time: The Origin and Evolution of the Party Coalitions -- Group Appeals and the Democratic Coalition -- The Politics of Democratic Disunity -- Variables Used in the Probit Equations in Chapter 3 -- Measuring Ideological Cohesion -- Open-Ended Responses on Group-Related Themes and Issues