Until the final quarter of the twentieth century, Western party systems appeared to be frozen, and stability seemed to be the central characteristic of individual-level party choice. Yet during the 1970s and 1980s, a spasm of change appeared to affect all countries, shaking the very foundations of this theory. Voters in Western countries demonstrated an unexpected and increasing unpredictability in their choices, often voting for parties that were quite new to the political scene. Understanding these fundamental changes became a pressing concern for political scientists and commentators alike. In the middle of the 1980s, leading scholars from across the world set out to explore the reasons for these shifts in sixteen Western countries: those belonging to the (then) European community (except for Luxembourg and Portugal), and Australia, Canada, New Zealand, Norway, Sweden, and the United States. This book reports on these findings regarding social divisions and party choice and the manner in which these links have changed since the mid-1960s. The authors build their case studies around a common research design, and in doing so, they are able to focus on the characteristics that these countries have in common and evaluate the extent to which their changes have a common source. Theirs is a longitudinal study, and its findings enable the authors to break away from conventional explanations for electoral change. This second edition augments the original text with a new preface noting the relevance of the book's findings to contemporary scholarship. An epilogue brings the main analyses up to date with the mid-2000s.