This study examines how participation in an online asynchronous discussion forum influences opinion changes and policy preferences regarding youth antisocial behavior. By randomly assigning online panel members to varying conditions of information provision and communication capabilities, we found that while forum engagement can lead to modest shifts in opinions among active contributors, the impact is limited due to the small, self-selecting group of participants and their minimal use of background information. This raises questions about the effectiveness of online forums in generating informed public input for policy-making.