In this paper we propose a method of feature selection using the AdaBoost algorithm for action recognition. Instead of detecting spatio-temporal interest points and using a ‘bag of features’ approach, we use densely sampled descriptors, either 3D-SIFT or 3D-HOG, and select the most discriminative subset using the AdaBoost algorithm. We obtain maximal accuracy with just 200 of the 3217 possible raw 3D features from each video sequence. Using the extremely simple naive Bayes nearest-neighbor (NBNN) classifier with the most discriminative 3D-SIFT features, we obtain accuracies of: 92.7%, 99.4%, 92.3% and 38.1% on the KTH, Weizmann, IXMAS and HMDB51 datasets, respectively. We also observe that the errors are reasonably equitably distributed across the different action classes.