During the twentieth century, local voluntary historic buildings preservation groups became an increasingly common feature of towns and cities across England. In their efforts to influence urban redevelopment, groups advanced notions of place and local identity reflective of the types of people who got involved, and they resorted to a range of strategic and tactical approaches to make their views known to decision-makers that were reflective of the skills mixes within their reach. Their public campaigns provoked new thinking about the balance between urban modernity and the historic setting that gained substantial currency during the twentieth century. However, there has been very little research into the historical dynamics of these groups, or the conditions under which they were able to influence the planning system. Previous research has instead focused on the development of legislation for the preservation of ancient monuments and historic buildings, and on national voluntary heritage groups operating from the metropolis. Local historic buildings preservation groups have been largely absent from histories of national planning legislation and voluntary action. This thesis seeks to fill the gap. It takes a local case-study approach to examine the experiences of local historic buildings preservation groups in five case study areas – Bath, Oxford, Reading, Southampton, and Winchester – over a period of about sixty-five years, from circa 1910 to the mid-1970s. The research makes extensive use of the records of local historic buildings preservation groups, many previously untapped by historians. It also uses the records of national voluntary organisations and local authorities to round out this picture and fill gaps in the documentary record. Through comparative study, the thesis identifies the critical conditions required for the successful instigation of a local historic buildings preservation group, accounting for the emergence of groups in historic cities such as Oxford and Bath in the 1920s and 1930s. The war years were a time of forward thinking for most groups, and the promise of urban planning to improve living standards in the postwar era attracted substantial public interest. Seeking to influence this picture, during the late 1940s and 1950s groups took hold in Southampton, Winchester and Reading, and the thesis compares their strategic development and tactical approaches, explaining the social and political dynamics influencing their trajectory. These efforts fuelled public debate over the impact of comprehensive redevelopment on historic cityscapes. Their influence was significantly bolstered in the late 1950s, when groups were networked by a new national body, the Civic Trust, which translated their local energy into legislative pressure. Ultimately, groups were able to foster their agendas more broadly, and play a role in the development of planning and conservation legislation. This had a transformative impact on social value for heritage and the influence of local groups on the planning system was more significant than has previously been recognised by historians.