Sabina Alkire shows how Nobel Prize-winning economist Amartya Sen's capability approach can be coherently—and practically—put to work in poverty reduction activities. Sen argues that economic development should expand "valuable" freedoms. Alkire probes how we identify what is valuable. Foundational issues are addressed critically—dimensions of development, practical reason, culture, basic needs—drawing on Thomist authors who give central place to authentic participation. A participatory procedure for identifying capability change is then developed. Case studies of three Oxfam activities in Pakistan—goat-rearing, female literacy, and rose cultivation—illustrate this novel approach.