This article reexamines the puzzling issue of where subjects, lexical and null,
are located in Spanish and offers a novel explanation for the incompatibility of
preverbal lexical subjects with fronted focussed constituents. Both SpecIP and
the left periphery appear to be potential landing sites for subjects, according
to discourse-pragmatic factors. Assuming that pro is a clitic,
it is argued that the aforementioned incompatibility can be captured by a simple
rule: SpecIP must be empty for focus fronting to occur. This is the case with
pro, which adjoins to Infl, or with postverbal subjects
since they remain in SpecVP. From this analysis it follows that: 1) the subject
field in Spanish is less articulated than is generally assumed, 2) the
differences between Spanish and other null subject languages with respect to the
availability of preverbal subjets can be reduced to this rule and a different
ordering of focus and topic phrases, and 3) it is unnecessary to posit two
different topic positions.