skills or knowledge of members of the public to supplement or create new information about archival collections (as opposed to platforms like facebook which primarily enable passing comments or indications of approval on content submitted by archivists). This incorporates a wide spectrum of participant behavior from the small, atomized contributions required to take part in the Old Weather transcription of ships' logs or to tag archival photographs on flickr commons , right through to the sustained effort and specialist knowledge needed to make a substantive contribution to The National Archives' wiki Your Archives . Flickr commons home page I'm particularly interested in what motivates people to participate online, so that we can establish what social and technical structures best support user participation, and feed this knowledge back into the design of future initiatives. Do online collaborative tools genuinely open up archives to crowds of 'new' users as is often claimed, or can the expertise of those with a prior interest and awareness of archives be more easily or usefully tapped? What mechanisms can be put in place both to encourage contributions and to establish the trustworthiness and relevance of submissions? I'm also interested to find out how potential contributors find out about online participation opportunities in the first place, and the interplay between different Web2.0 tools in promoting such projects. Some of the initial data I've collected suggests that although social media like twitter and facebook can play an important role in raising awareness amongst fellow professionals of new projects,