The paper discusses aspectual distinctions among Polish nominalizations belonging to different semantic domains, in particular action nominals and psych nominals. It is demonstrated that in Polish there are two types of nominals that qualify as complex event nominals in the understanding of Grimshaw 1990: aspectually ambiguous derived nominals whose properties are like those of English derived nominals and verbal nouns which have grammatical aspect and form aspectual pairs like the related verbs. It is argued that not only action nominalizations but also psych nominalizations denote complex eventualities, except that in the former the culmination point terminates the eventuality whereas in the latter it is at the beginning. The perfective/imperfective contrast is taken as evidence for the complexity of the eventuality and the heterogenous nature of the component subevents. In conclusion, it is suggested that the atomic Vendlerian taxonomy of event types is insufficient for the analysis of different types of complex events and furthermore that the overt aspectual distinctions among Polish nominalizations belonging to different semantic domains might be also present covertly in other languages, which leads to ambiguities of various sorts.