Starting a new online community with a limited number of members who have not self-selected for participation in the community is challenging. The space must appear active to lure visitors to return; when the pool of participants is small, a large fraction must be converted from lurkers to contributors, and contributors must receive responses quickly to encourage continued participation. We report on strategies for overcoming these challenges and our experience implementing them within an online community add-on to an existing Internet-mediated walking program. Concentrated study recruitment increased the effective membership size. Having few conversation spaces rather than many specialized ones, staff seeding of the forums before members were invited to visit, and staff posting of new topics when there were conversation lulls, all helped to make the forums appear active. In retrospect, using even fewer separate spaces and displaying a flat rather than nested reply structure would have made the forums appear even more active. Contests with small prizes around participation in the forums and around meeting walking goals generated a lot of discussion; a contest for first-time posters was especially effective at moving lurkers to post. Staff efforts to elicit participation by asking questions had mixed success. Staff replies to posts that had not received member replies created a feeling of responsiveness despite limited membership.