The monograph provides the first comprehensive description of the category of verbal aspect in modern Slovene. The functioning of verbal aspect on the word-formation and semantic levels, which are closely intertwined, is examined in detail, while the syntactic level complements them frequently. Although in Slovene the change of verbal aspect (perfective : imperfective or vice versa) in transition between different syntactic contexts is somewhat less pronounced than, for example, in Russian, the category of verbal aspect nevertheless remains an important part of its grammatical system. Thus, in the SSKJ (The Dictionary of the Slovenian Standard Language) one can observe the unification of dictionary definitions in cases where semantic difference between the meanings of the verbs of opposite aspect approaches 0 (aspectual correlates). Such a relationship in at least one of the meanings of the verbs of opposite aspect is termed aspectual correlation – it occurs not only in the relationship between verbal derivatives by prefixation and their derivations (e. g. sestaviti : sestavljati), but also between non-prefixed imperfectives and derivatives by prefixation containing prefixes with high aspectual-correlation potential (e. g. kuhati : skuhati, brisati : pobrisati/obrisati, pisati : napisati; kašljati : zakašljati).