Landslides are an abundant feature of the Italian landscape, where they present both a major natural hazard and a rich source of data for the study of geomorphic processes. We have the Collazzone region of central Umbria as the focus for a study of landslide mechanisms. We propose to combine high resolution (1m) LIDAR terrain data with existing multitemporal maps of landslides to investigate the following: (1) the relationships among the surface morphology, the pattern of past and present landslides, and the triggering of subsequent hillslope failures; (2) the relationship between patterns of real and modeled hillslope instability - the latter derived from a model of rainfall, runoff and soil saturation, based on the LIDAR terrain model, and validated through field observation and monitoring. The landslide data for Collazzone, rigorously mapped and extensively field validated (by CNR-IRPI Perugia), represents an excellent basis for the quantitative study of topographic relief and mass-wasting. The high spatial precision of both the LIDAR topographic data and the landslide maps will permit a detailed investigation of the development of landslide complexes in particular, how and where subsequent slope failures are determined by pre-existing failures, and whether such relationships are dominantly morphological or mechanical.