Abstract Automatic argument generation is an appealing but challenging task. In this paper, we study the specifific problem of counterargument generation, and present a novel framework, CANDELA. It consists of a powerful retrieval system and a novel two-step generation model, where a text planning decoder fifirst decides on the main talking points and a proper language style for each sentence, then a content realization decoder reflflects the decisions and constructs an informative paragraph-level argument. Furthermore, our generation model is empowered by a retrieval system indexed with 12 million articles collected from Wikipedia and popular English news media, which provides access to highquality content with diversity. Automatic evaluation on a large-scale dataset collected from Reddit shows that our model yields signififi- cantly higher BLEU, ROUGE, and METEOR scores than the state-of-the-art and non-trivial comparisons. Human evaluation further indicates that our system arguments are more appropriate for refutation and richer in content