摘要:Newcomer participation is a strong determinant of the success of online communities, particularly of open source software (OSS) development communities. Most research on newcomer participation in online communities so far has been limited to understanding the socialization experiences of participants once they join a community. No study we are aware of has looked at the role of factors external to a community itself in determining participation levels. We argue that it is important to understand external factors to delineate accurate reasons for decline or growth of participation in a community. In this study, we investigate the effect of company announcements made by OSS steward firms, events which are external to a community, on participation in newcomer communities associated with the OSS. We studied activity in two communities, a Java newcomer forum and a MySQL newcomer forum, around two announcements that affected each community. We found evidence that company announcements had a substantial effect and participation either increased or decreased. Through analysis of secondary sources we conjecture that announcements indirect shape participation by influencing newcomer motivation. Announcements perceived as hostile to open source values have a significant negative effect on participation, whereas announcements perceived as friendly either significantly increase participation or have no significant effect.