Enhancing Quality of Life (QOL) has long been an explicit or implicit goal for individuals, communities, nations, and the world. But defining QOL and measuring progress toward meeting this goal have been elusive. Diverse “objective” and “subjective” indicators across a range of disciplines and scales, and recent work on subjective well-being (SWB) surveys and the psychology of happiness have spurred interest. Drawing from multiple disciplines, we present an integrative definition of QOL that combines measures of human needs with subjective well-being or happiness. QOL is proposed as a multi-scale, multi-dimensional concept that contains interacting objective and subjective elements. We relate QOL to the opportunities that are provided to meet human needs in the forms of built, human, social and natural capital (in addition to time) and the policy options that are available to enhance these opportunities. Issues related to defining, measuring, and scaling these concepts are discussed, and a research agenda is elaborated. Policy implications include strategies for investing in opportunities to maximize QOL enhancement at the individual, community, and national scales.