Title: Automatic Data Augmentation for Generalization in Reinforcement Learning. Abstract: Deep reinforcement learning (RL) agents often fail to generalize beyond their training environments. To alleviate this problem, recent work has proposed the use of data augmentation. However, different tasks tend to benefit from different types of augmentations and selecting the right one typically requires expert knowledge. In this paper, we introduce three approaches for automatically finding an effective augmentation for any RL task. These are combined with two novel regularization terms for the policy and value function, required to make the use of data augmentation theoretically sound for actor-critic algorithms. We evaluate our method on the Procgen benchmark which consists of 16 procedurally generated environments and show that it improves test performance by 40% relative to standard RL algorithms. Our approach also outperforms methods specifically designed to improve generalization in RL, thus setting a new state-of-the-art on Procgen. In addition, our agent learns policies and representations which are more robust to changes in the environment that are irrelevant for solving the task, such as the background. 