The article compares the occurrence of pronominal possessive adjectives and denominal group adjectives in Polish event nominals. It is demonstrated that while in other Slavonic languages (e.g., in Russian) relational adjectives clearly contrast with possessive adjectives (both pronominal and lexical ones), in Polish denominal group adjectives, such as prezydencki ‘presidential’, ministerialny ‘ministerial’, or urzędniczy ‘clerk.ADJ’, resemble possessive pronouns in functioning as elements which can satisfy the argument structure of event nominals. The focus is laid on intransitive nominals, in view of the Possessor Principle proposed for Polish by Rozwadowska (1997). While some Polish intransitive nominals accompanied by possessives or by group adjectives are recognized as referential nominals (as is predicted by the analysis of Greek and Romanian group adjectives presented by Alexiadou and Stavrou, 2011, and Moreno, 2015), other intransitive nominals with such adjectival satellites are argued to be argument-supporting nominals. The association with the agentive reading (i.e., external argument interpretation) is shown to be characteristic, but not obligatory, with thematic group adjectives.