This dissertation suggests that referential 3rdP null subjects in Modern Brazilian Portuguese (BP) and Finnish are residues of A-movement, rather than null pronouns. These grammars exhibit weak 3rdP verbal and possessive agreement morphology, and do not obey the Avoid Pronoun Principle, allowing non-emphatic overt pronouns in subject position. This state of affairs has affected the licensing of referential null subjects, which are licensed only within embedded domains. I correlate the loss of agreement with this peculiar behavior of null subjects and advance the hypothesis that BP and Finnish are not pro-drop grammars, arguing on empirical grounds that in BP and Finnish null subject inside the embedded clauses and possessive DPs are residues of A-movement. Putting it boldly, these null subjects are salient copies of their antecedents. The arguments I present in favor of a movement analysis are: (i) Finnish and BP null subjects have an anaphoric behavior, requiring a sentential antecedent, which is the closest c-commanding DP. (ii) They cannot occur within relative clauses if the head of the relative clause intervenes between them and their antecedents. (iii) They display all the diagnostics used to characterize obligatory control as formed by movement; (iv) They do not occur inside paratactic constructions. (v) Inside coordinated DPs, they must occur in an across-the-board fashion. (vi) Floating quantifiers and participial forms within their c-command domains agree with their antecedents in f-features. Presupposing that in pro-drop languages pro is the verbal agreement morpheme (Agr) itself, I suggest in that in BP and Finnish Agr underwent f-degradation and was lexically reanalyzed as part of the verb. However, it is hypothesized that in these languages Agr retained a D-feature, and, consequently, it can satisfy the EPP feature of a Case-checking functional projection. As result, in these grammatical systems, a DP can undergo A-movement out of a Case-domain.