A light detection and ranging (lidar) canopy height study was conducted with 13 datasets collected using four different models of airborne laser terrain mapper (ALTM) sensors over 13 widely variable vegetation types ranging in average height from <1 m to 24 m at five sites across Canada between 2000 and 2005. The study demonstrates that the vertical standard deviation of all topographically detrended first and last laser pulse returns (LSD) is a robust estimator of canopy height (Ht) for a wide variety of vegetation types and heights and lidar survey configurations. After regressing Ht against LSD for 77 plots and transects, it was found that Ht could be predicted as a simple multiplication (M) of LSD (M = 2.5, coefficient of determination (r2) = 0.95, root mean square error (RMSE) = 1.8 m, tail probability (p) < 0.01). For forest plots only, LSD was found to better predict average tree height (r2 = 0.80, RMSE = 2.1 m, p < 0.01) than Lorey's height (r2 = 0.59, RMSE = 3.0 m, p < 0.01). A test of the LSD ca...