Both work groups and nascent peer production projects are composed of a small group of people, engaged in collaborative sense-making and knowledge production. The work group literature has found that dense, non-hierarchical interaction structures are associated with productive groups. Based on these findings, we hypothesize that these same structures would also lead to more productivity from new peer production communities. However, an analysis of 2,555 wiki communities shows that early interaction structures have very little impact on eventual productivity (as measured by total edits) or community growth (as measured by total contributors). Rather, a quickly growing group of active editors is a much better predictor of growth than the structure of interactions between them.