Land Use Planning (LUP) is a central tool of public policy for promoting Sustainable Land Management (SLM) in social-ecological systems of drylands, considering the strong dependence between local communities and their natural resources. This work highlights the collective process carried out for achieving the Diagnosis of the physical-biological subsystem and for formulating conservation and SLM strategies in La Paz department, Argentina, within the framework of the LUP Municipal Plan (LUPMP). To do so, a methodology that combines participatory techniques, like collective mapping, with use of geographic information systems (GIS) and remote sensing. The collective construction of knowledge, through interaction among the scientific, governmental and local communities, allowed to define and validate eight Territorial Integration Units, priority sites for conservation of the natural and cultural heritage, SLM practices and LUP programs. The resulting Diagnosis constitutes a key information input for making decisions aimed at sustainability, replicable in other drylands.