This paper examines the so-called internally headed relative clause construction in Japanese, with particular focus on new data that involve quantificational NPs and wh-phrases. The data provide arguments for representations in which the internal head remains internal at LF. Furthermore, it is shown that the interpretation of this construction involves E-type anaphora, providing evidence for Hoshi's (1995) suggestion. An explicit mechanism for compositional interpretation is proposed, which also derives a restriction on possible internal heads. This study has the cross-linguistic implication that the constructions called “internally headed relative clauses” in various languages do not form a homogeneous class.