The elevation at which wildfire smoke is injected into the atmosphere has a strong influence on how the smoke is dispersed, and is a key input to aerosol transport models. Aerosol layer height is derived with great precision from space-borne lidar, but horizontal sampling is very poor on a global basis. Aerosol height derived from space-borne stereo imaging is limited to source plumes having discernable features. But coverage is vastly greater, and captures the cores of major fires, where buoyancy can be sufficient to lift smoke above the near-surface boundary layer. Initial assessment of smoke injection from the AlaskaYukon region during summer 2004 finds at least about 10% of wildfire smoke plumes reached the free troposphere. Modeling of smoke environmental impacts can benefit from the combined strengths of the stereo and lidar observations.