This paper offers an explanation for the curious fact that Dutch R-pronouns cannot strand P under sluicing, contrary to what we expect based on Merchant's (2001) P-stranding generalization. I argue that R-words are categorically and semantically underspecified and obtain their function and meaning throughout the derivation. The pronominal meaning requires P to be overt, both in ellipsis and in other contexts such as relative clauses headed by a PP. For the former context, pied-piping is then required to license that meaning. If not, the resulting derivation violates e-GIVENness because a locational variable is licensed instead.