Abstract: User-generated content (UGC) may be dynamically inserted into an advertisement (such as a web advertisement) or other media. UGC may be selected for insertion based on attributes of a target user or viewer (e.g., a person who will view an advertisement in a web browser). UGC may also be selected based on attributes of a contributor of UGC. For example, UGC authored by an expert male video-game player may be selected for insertion in an advertisement that is targeted to users who may be likely to be influenced by such a person. Conversely, target users that may not be a good match with a given contributor may not have content from the given contributor presented to them in an advertisement or other media. Weighted scoring mechanisms may determine whether a contributor of UGC is considered to be a match for a target user.