Alkire examines how Nobel Prize-winning economist Amartya Sen's capability approach can be coherently-and practically-put to work in participatory poverty reduction activities. Sen argues that economic development should expand 'valuable' capabilities. Alkire probes how we identify what is valuable. Sen deliberately left the capability approach 'incomplete' in order to ensure its relevance to persons and cultures with different understandings of the good. Part I proposes a framework for identifying valuable capabilities that retains this 'fundamental' incompleteness and space for individual and cultural diversity. Drawing on the work of John Finnis and others, Alkire addresses foundational issues regarding the identification and pursuit of 'valuable' dimensions of human development based in practical reason, then observes that much of the criticism of development arises from negative impacts on social or cultural/religious dimensions that are also deeply valued by the poor. Part I closes with a four-part 'operational definition' of basic capability that bridges 'basic needs', participation, and informed consent. Part II proposes an alternative participatory method for systematically identifying valued changes in participants' capability sets. Three case studies of women's income generation activities in Pakistan--goat-rearing, adult literacy, and rose cultivation--contrast economic cost-benefit analysis of each activity with capability analysis.