Since Rizzi's (1986) seminal work on phonologically null pronominals, how to derive the classification of the so-called pro-drop languages has long been controversial in the literature. Various alternative proposals emerged, and we have gained some understanding of some nontrivial generalizations behind the phenomenon, and a number of interesting empirical facts have also been accumulated. In general, we have learned a great deal about the nature of the phenomenon. In spite of this tradition, there have never been any analyses without recourse to Pro Module, a subtheory of grammar whose status in the architecture of language is unclear, which is mysterious given the reformulation of the so-called GB framework into the minimalist program from the latter half of the 1990s. This paper is an attempt to derive the effects of Pro Module solely from the morphological properties of functional elements T and AGR. Specifically, an optional syntactic feature [+F] at the head T and a parametric notion of [ d: Inherent] AGR are introduced. An immediate theoretical consequence of this proposal is that we need not invoke any independent subtheory of grammar such as Pro Module to explain the occurrence of pro . In addition, no parametric stipulation concerning a set of formal licensers is needed. The proposed analysis also has an empirical advantage in that it can cover a wider range of pro-drop languages than Rizzi's. In particular, it is shown that Sentential Subject Constructions and Locative Inversions in English are given a unified analysis on the assumption that expletive pro is available in those constructions, which implies that English is included in the class of pro-drop languages, in contrast to the prevailing view among generative grammarians. identifier:7 identifier:KJ00004256362