This book provides a novel account of the Labour Party's years in opposition and power since 1979, examining how New Labour fought to reinvent post-war social democracy, reshaping its core political ideas. It charts Labour's sporadic recovery from political disaster in the 1980s, successfully making the arduous journey from opposition to power with the rise (and ultimately fall) of the governments of Tony Blair and Gordon Brown. Forty years on from the 1979 debacle, Labour has found itself on the edge of oblivion once again. Defeated in 2010, it entered a further cycle of degeneration and decline. Like social democratic parties across Europe, Labour failed to identify a fresh ideological rationale in the aftermath of the great financial crisis. Drawing on a wealth of sources including interviews and unpublished papers, the book focuses on decisive points of transformational change in the party's development raising a perennial concern of present-day debate - namely whether Labour is a party capable of transforming the ideological weather, shaping a new paradigm in British politics, or whether it is a party that should be content to govern within parameters established by its Conservative opponents. This text will be of interest to the general reader as well as scholars and students of British politics, British political party history, and the history of the British Labour Party since 1918.