Abstract: Systems and methods for suggesting a thread in an online group is disclosed. The method includes the following steps. First, the system calculates an average in-reply time to each user in the online group on history data. Second, the system calculates an average out-reply time from each user in the online group on history data. Third, the system identifies, in a computer, a root message in the thread by a first author. Fourth, the system identifies a second message in the thread that follows the root message. Fifth, the system determines an estimated growth rate of the thread based on average in-reply time and average out-reply time of the first author and a time delay between the second message and the root message. Finally, the system suggests the thread to users in the online group according to the estimated growth rate of the thread.