The ef fi cacy and use of volunteered geographic information (VGI) is an active research area, but the geography of VGI authorship is largely unknown. Wikipedia is an online collaborative encyclopedia where anyone can edit articles, including those about place. Moreover, Wikipedia's editorial transparency facilitates in situ observations of collective authorship. The empirical study described in this chapter collects 32 million contributions to Wikipedia's geographic articles over 7 years. It fi nds exponential decay in the spatial patterns of Wikipedia's authorship processes, which is consistent with other sociospatial phenomena, like innovation diffusion. As global information infrastructures continue to reduce communication and coordination costs, this study may provide insight into whether geographic distance ultimately matters in information peer production. This chapter begins by discussing core concepts behind collective authorship; then provides an overview of Wikipedia, its contributors, and their production processes; discusses the results and implications from spatial modeling of geotagged Wikipedia article contributions; and concludes with future research issues.