It is our great pleasure to welcome you to the Sixth Workshop on Natural Language Processing for Social Media-SocialNLP 2018, associated with ACL 2018. SocialNLP is an inter-disciplinary area of natural language processing (NLP) and social computing. We hold SocialNLP twice a year: one in the NLP venue, the other in the associated venue such as those for web technology or artificial intelligence. There are three plausible directions of SocialNLP: (1) addressing issues in social computing using NLP techniques; (2) solving NLP problems using information from social media; and (3) handling new problems related to both social computing and natural language processing. Through this workshop, we anticipate to provide a platform for research outcome presentation and head-to-head discussion in the area of SocialNLP, with the hope to combine the insight and experience of prominent researchers from both NLP and social computing domains to contribute to the area of SocialNLP jointly. The submissions to this year's workshop were again of high quality and we had a competitive selection process. We received submissions from Asia, Europe, and the United States, and due to a rigorous review process, we only accepted 7 long oral papers among 19. Thus the acceptance rate was 37 percent. In addition, we are having our first research challenge: EmotionX in the SocialNLP workshop. A total of 18 groups registered for the dataset and at last 5 groups submitted their results successfully. Therefore these year we have 7 research papers, 1 challenge overview paper as well as 5 challenge papers, that is, a total of 13 papers published in the proceedings of the ACL chapter for the SocialNLP 2018 workshop. This year, we are excited to have Dr. Saif Mohammad from National Research Council Canada, and Dr. Yi-Chia Wang from Uber as our keynote speakers. We also encourage attendees to attend the keynote talk presentations to have more discussions with outstanding researchers. Their valuable and insightful talk can and will guide us to a better understanding of the future. Putting together SocialNLP 2018 was a team effort. We first thank the authors for providing the quality content of the program. We are grateful to the program committee members, who worked very hard in reviewing papers and providing feedback for authors. Finally, we especially thank the Workshop Committee Chairs Prof.