ABSTRACTSocial question answering (SQA) sites have become a popular online community platform for information seeking and social interaction. Prior SQA research has focused more on questions and answers, but has not examined user roles and their characteristics and activity patterns. In this poster, we identified four collaborative roles (starter, answerer, technical editor and follower) inZhihu.com, a popular expert SQA site in China, and examined their characteristics and activity patterns. Our data set contained 14,779 users, 2,362 questions, and 8,486 answers from 12 health‐related topics. Results show that, starters and technical editors ask more questions, make more technical edits, answers a few questions, and are not well connected to other users. Answerers contribute more content, attract the most followers and received the most likes and votes. Followers contribute little content, and receive the least likes and votes, but follow more topics and users. Content contributing activities such as answering questions gain more likes and votes, but posting a question and making a technical edit can get more pageviews. Users have overlapping roles and more research is needed to fully understand the interaction and interplay among user roles in SQA collaboration.