Title: SDNet: Contextualized Attention-based Deep Network for Conversational Question Answering. Abstract: Conversational question answering (CQA) is a novel QA task that requires the understanding of dialogue context. Different from traditional single-turn machine reading comprehension (MRC), CQA is a comprehensive task comprised of passage reading, coreference resolution, and contextual understanding. In this paper, we propose an innovative contextualized attention-based deep neural network, SDNet, to fuse context into traditional MRC models. Our model leverages both inter-attention and self-attention to comprehend the conversation and passage. Furthermore, we demonstrate a novel method to integrate the BERT contextual model as a sub-module in our network. Empirical results show the effectiveness of SDNet. On the CoQA leaderboard, it outperforms the previous best model's F1 score by 1.6%. Our ensemble model further improves the F1 score by 2.7%.