This chapter presents the processes and outcomes of a participatory action-research project (PAR) for sustainable development in Acostambo, a rural municipality in the Peruvian Andes. The HSD framework provides a methodology for societies, communities or groups to engage in their own sustainable development path by mobilising endogenous potentials and encouraging self-reliance. It seeks to contribute to debate about the operationalisation of sustainable development by presenting a PAR project based on the Human Scale Development (HSD) approach. The chapter starts by introducing HSD approach as a tool for sustainable development through its focus on human needs satisfaction, self-reliance and balance interdependence of people, nature and technologies. Next, this chapter presents the processes and outcomes of the PAR study illustrated by the organic vegetable gardens strategy, the one prioritised by participants as having potentially greater effects on human needs. The outcomes of the PAR project discussed with regards to the achievement of higher levels of human needs satisfaction and environmental conservation.