Many recent annotation efforts for English have focused on pieces of the larger problem of semantic annotation, rather than initially producing a single unified representation. This paper discusses the issues involved in merging four of these efforts into a unified linguistic structure: PropBank, NomBank, the Discourse Treebank and Coreference Annotation undertaken at the University of Essex. We discuss resolving overlapping and conflicting annotation as well as how the various annotation schemes can reinforce each other to produce a representation that is greater than the sum of its parts.