We introduce a modular, dependency-based formalization of Information Structure (IS) based on Steedman's prosodic account (Steedman 2000, Steedman 2000a). We state it in terms of Extensible Dependency Grammar (XDG) (Debusmann et al. 2004), introducing two new dimensions modularly modeling 1) prosodic structure, and 2) theme/rheme and focus/background partitionings. The approach goes without a non-standard syntactic notion of constituency, and can be straightforwardly extended to model interactions between IS and other dimensions such as word order.