sentences: Despite their massivesize, successful deep artificial neural networkscan exhibit a remarkably small differencebetween training and test performance. Conventional wisdom attributessmall generalization error either to propertiesof themodel family, or to the regularization techniquesused during training. Through extensive systematic experiments, we show how these traditional approaches fail to explain why large neural networks generalize well in practice. Specifically, our experimentsestablish that state-of-the-art convolutional networks for image classification trained with stochastic gradient methods easily fit a random labeling of the training data. This phenomenon is qualitatively unaffected by explicit regularization, and occurs even if we replace the true images by completely unstructured random noise. We corroborate these experimental findings with a theoretical construction showing that simpledepth two neural networksalready haveperfect finitesampleexpressivity assoon as thenumber of parameters exceeds thenumber of datapointsas it usually does in practice. We interpret our experimental findingsby comparison with traditional models.