This paper presents a new contrastive analysis of the expression of referential pronominal subjects in European Portuguese (EP) and Brazilian Portuguese (BP), based on two recent samples, recorded in Lisbon and Rio de Janeiro, in 2009-2010, according to the same social stratification. The results reinforce EP’s status of a “consistent” Null Subject Language (NSL) (Roberts and Holmberg, 2010) and allow to follow the change in course in BP by offering answers to the empirical problems posed by Weinreich, Labov and Herzog (1968), particularly those related to the constraints and to the embedding of the change. Inherently human referents have been the most remarkable feature in the process, since 2nd person overt subjects lead the change and reveal an almost complete stage. The slower course of the change with 3rd person referents confirms the role of animacy in the process: [+human/+animate] subjects are preferably overt, whereas [-animate] subjects show more resistance in spite of a significant rise in the rate of overt pronouns when compared to a sample of the same speech community recorded in 1992. A multivariate analysis of 3rd person in both varieties points out the same structural relevant factors constraining overt/null subjects: the structural pattern (function of the antecedent), the cluster of semantic features of the referent (animacy and specificity) and the structure of the Complementizer Phrase (CP). The comparison allows to claim that the multivariate analysis is a powerful instrument to understand the internal factors controlling [+/- prodrop] systems. Even though rates of overt subjects are significantly higher in BP, already outnumbering null subjects in every structural environment (contrary to what is found for EP), Relative Weights obtained reveal the same effects in both varieties. Moreover, the analysis reveals some important evidence of the embedding of the change, in the present case, supporting the hypothesis of the resetting of the Parameter value by BP – from a NSL to a non-NSL.