The paper focuses on contrastive semantics of phase verbs or aspectualizers in English and Serbian, taking into account both typical and atypical phase verbs. Following Piper (Piper et al. 2005), we adopt the class of atypical aspectalizers in Serbian which are primarily lexical verbs but yield an aspectual meaning when combined with an aspectual complement. We specifically consider phase verbs BEGIN and START in English and their Serbian equivalents POČETI and KRENUTI. Alternatively to both traditional and more contemporary linguistic approaches to phase verbs in English and Serbian, we claim that the true overall linguistic equivalent of the English phase verb START is not Serbian phase verb POČETI, but another, atypical aspectualizer KRENUTI. We base this claim on the equivalency of contrastive syntactic complementation of the inspected aspectualizers, as well as their argument structure, taking into account Freed’s (Freed 1979: 31) traditional view of the aspectual event, where the event is segmental, containing the onset, the nucleus, and the coda. Freed’s account is combined with the lexical-projectionist model proposed by Levin (Levin 1993) alongside the grammar of constructions (Goldberg 1995, 2006). Additionally, alternatively to the generally accepted claim that all phase verbs in Serbian as a rule take imperfective verbs as their complements (Ivić 1970: 44), we claim that KRENUTI with additional, phase-related meanings frequently and productively allows for perfec- tive complementation. The present analysis is backed up by a parallel corpus of English and Serbian sentences compiled from the British National Corpus, the Corpus of Contemporary American English, and the Corpus of Contemporary Serbian Language.