PL
The following paper addresses the issue of constructions with predicative adjectives in Polish. The main focus of attention will be put on adjectives which are governed by the copula in the infinitive form, as here one can observe some interesting casus alternation between the nominative and the instrumental. On the basis of the author’s own empirical analysis it will be examined which factors determine the choice of the casus. As it seems it is both the syntactic status of the infinitive construction and lexical factors.