Airborne Laser Scanning (ALS), or Light Detection and Ranging (LIDAR) is an emerging remote sensing technology that is rapidly gaining acceptance as the optimal methodology/technology for characterizing the 3-D, vertical structure of forested vegetation and developing digital terrain models of both canopy and bare earth.  Assessment of forest canopy and sub-canopy vertical structure will not only advance DOD’s understanding of complex forest ecosystems in support of environmental sustainment (e.g.  TES habitat assessment, infiltration and erosion potential, fire fuel modeling, damage assessment and monitoring) but also support critical warfighter requirements (e.g. line of sight, tactical concealment, trafficability, precision weapon/target guidance) and site evaluation for renovation/construction/engineering.   This paper will provide examples of development of extremely accurate and detailed bare earth digital terrain models (DTM’s) from LIDAR data, even in closed canopy environments.  It will also demonstrate the utility of LIDAR for characterizing mid-story structure, which previously has not been possible with traditional, optical satellite imagery and aerial photography.  Specific examples will include LIDAR data analysis as a tool to describe the vertical composition of forest and to aid in the analysis of canopy structure and its role in habitat selection by several threatened and endangered species on military lands.  Examples will also include assessment of LIDAR data for improved characterization and monitoring of erosion status and potential on military lands.  The techniques and protocols for analyzing LIDAR that have been developed are also adaptable to support other applications that require an assessment of the vertical distribution and structure of vegetation, a detailed digital terrain model of the top of the forest canopy, or a detailed digital terrain model of bare earth