This study investigates the argument patterns in Yahoo! Answers, a major question and answer (Q&A) site. Mainly drawing on the ideas of Toulmin (2003), argument pattern is conceptualized as a set of 5 major elements: claim, counterclaim, rebuttal, support, and grounds. The combinations of these elements result in diverse argument patterns. Failed opening consists of an initial claim only, whereas nonoppositional argument pattern also includes indications of support. Oppositional argument pattern contains the elements of counterclaim and rebuttal. Mixed argument pattern entails all 5 elements. The empirical data were gathered by downloading from Yahoo! Answers 100 discussion threads discussing global warming—a controversial topic providing a fertile ground for arguments for and against. Of the argument patterns, failed openings were most frequent, followed by oppositional, nonoppositional, and mixed patterns. In most cases, the participants grounded their arguments by drawing on personal beliefs and facts. The findings suggest that oppositional and mixed argument patterns provide more opportunities for the assessment of the quality and credibility of answers, as compared to failed openings and nonoppositional argument patterns.