Proceeding from observations on the apparently heterogeneous nature of language-specific properties of topicalization constructions, the study embarks on a universal-grammar analysis attempting to provide a systematic and uniform approach to various individual-language phenomena such as the contrast between topicalization in and out of infinite clauses, the apparent acceptability of NegP topicalization, and that of multiple topicalization in languages like German, English and Korean. The author demonstrates that these differences result from the parametricalization of the property-strength of separate functional categories for topic and focus in the framework of Chomsky's Minimalist Program (1995).