Rangelands in temperate areas provide food to herds of domesticated animals and, therefore, provide the infrastructure for two major industries: (a) the meat industry that feeds large populations around the globe; and (b) the wool industry that uses fibre from sheep. In the semiarid zone, rangelands have a socio-economic role as they support the economy and culture of pastoral societies. However, despite their importance, rangelands are under constant threat due to encroachment by humans and invasion by noxious plants, due to degradation and erosion processes and due to drought effects. Remote sensing can be used to identify and monitor the threats to ecological processes in rangelands and, thus, to their ecological sustainability. This article provides a review of the scientific literature on the remote sensing of rangelands and discusses recent developments with respect to mapping thematic classes of vegetation and vegetative cover, mapping biophysical properties such as primary production, and monitoring land-use changes, including those driven by anthropogenically enhanced processes such as soil erosion. In the light of the reviewed studies, we expect that future research on monitoring rangeland sustainability with remote sensing will focus on hyperspectral measurements of the spectra of rangeland plant species, on lidar measurements of canopy height, and on synthetic aperture radar for biomass assessment. In the long-term, more predictive (or at least heuristic) modelling of degradation scenarios due to erosion, invasion of noxious species, and land-use transformations can be anticipated.