Airborne lidar systems have proven very useful for atmospheric and oceanic studies during the past three decades and more recently for surface and vegetation canopy studies. Typical applications of airborne lidar for atmospheric studies include studying the long-range transport of pollutants, taking large-scale surveys of tropospheric aerosols and ozone (O3) over remote regions of the Earth, studying water vapor (H2O) and the hydrologic cycle, and investigating various processes associated with biomass burning emissions, desert dust transport, stratospheric aerosol transport following volcanic eruptions, polar O3 changes, and polar stratospheric clouds (PSCs), and metal ion concentrations in the ionosphere. Airborne lidar systems that are participating in studies of aerosols, O3, and H2O can also be used to make correlative measurements of space-based remote-sensing instruments and serve as test beds on the way to space-based lidar systems.