Between 1950 and 2010, the British co-operative movement faced a series of commercial, structural, and corporate governance crises. Having pioneered many of the features of modern large-scale retailing since its origins in the mid-nineteenth century, from the 1950s the Co-operative Wholesale Society (CWS) and the retail cooperative societies it served experienced plummeting market share, continued internecine rivalries, and increasing marginalization. In the early twenty-first century, however, co-operatives improved their market share and experienced a “Renaissance” in commercial fortunes despite continued fierce competition in food retailing. As yet there has been little exploration of the nature of this turnaround and the ways in which the once-foundering co-operative business model was re-engineered. Drawing on new research into the CWS (renamed The Co-operative Group in 2001), this article provides a historical analysis of the movement’s decline and revival. As the article details, from the 1950s significant efforts were made to reform CWS and the movement as a whole. However, co-operatives were slow to adapt to the changing business environment, hampered by dysfunctional organizational dynamics that constrained structural change and limited efforts to compete with private retail multiples. Following an unsuccessful takeover bid for CWS in 1997, co-operative opinion coalesced around the need for change. In the final section, the authors analyze the factors underpinning the “Renaissance,” focusing on both organizational innovations and the reassertion of core values and principles on which co-operation had been built. This provides a fascinating illustration of how a business can respond effectively to internal and external challenges, yet retain its fundamental character.