Nepstad provides a useful survey of twentieth-century lay Catholic activism in the United States in what she considers the arenas of progressive social activism: workers’ rights; peace and disarmament; women's equality; liberation theology/ US foreign policy in Latin America; immigration; and the environment. This book is written, in some ways, for a non-specialist, with the blurb on the back cover beginning: ‘Most Americans assume that the Catholic Church is inherently conservative.’ She sets out to disavow the general public and scholars, who may have it, of this assumption. She begins appropriately with Catholic theology, focusing initially on Pope Leo xiii's encyclical Regium novarum (1890) which critiqued late nineteenth-century laissez-faire capitalism and established Catholic social thought as active in the public political realm and not just in private acts of charity. As a result, the nascent American labour movement received a lot of support from lay Catholics. Following this examination of Catholic support for workers, Nepstad continues to weave Catholic theology into her account of each area of progressive concern. She concentrates on lay organisational efforts to support labour, women's rights, the environment etc. (though not averse to homing in on some significant individuals). Overall, Nepstad provides a good guide to Catholic lay activism, and promotes its significance in driving Church policy, but a lot of this lay work still had serious clerical and religious involvement. For example, Catholic Climate Covenant, led by a lay Catholic, which campaigns against climate change, was created by the American Conference of Catholic bishops. Success or failure in driving for change from below within the Church still very much depended on clerical approval. The efforts to change official Catholic theology around birth control, for example, have failed. This volume is quite comprehensive, though Nepstad only mentions Catholic action against the death penalty and euthanasia once, towards the end, perhaps because these campaigns are too much wrapped up in the anti-abortion agenda of the larger pro-life Catholic movement, and thus do not fit within her definition of progressive social activism. Overall, she concludes, lay Catholic social activists play a vital role in turning theology and encyclicals into ‘living religion’ (p.163).