An analysis of null object constructions in colloquial Brazilian Portuguese is brought to bear on the theory of empty categories. Focusing on their properties in adjunct clauses, it is argued that at least some null objects must be analyzed as pro's, even though they are not morphologically identified. An empty topic variable approach (Huang, 1984) is argued to be empirically inadequate and to have no explanatory advantage over an analysis on which all null objects are pro's, in spite of the fact that there exist gaps in the distribution of null objects that appear to support the empty topic hypothesis. Brazilian Portuguese is shown to be a language that requires subject pro to be identified. It is suggested that object pro must also be identified and that the notion of what counts as identification must be broad enough to include the possibility of intrinsic specification of features. In the absence of identifying features on its govverning head, pro is predictably third person.