Summary In this article a parallel is drawn between certain functions of irrealis and imperfective in evaluating contexts in Russian and Polish. The functions of irrealis in complementation are twofold: while in propositional complements it reflects irreality, in state-of-affairs complements it reflects temporal and situational unanchoring. This unanchoring function manifests itself also in complements of evaluative (commentative) predicates, where it extracts an event from its situational setting for the purpose of evaluating its intrinsic properties – intrinsic likelihood or desirability. It is argued that the representation of event tokens as event types by means of imperfective verbs in Slavonic performs a similar unanchoring function in evaluative contexts. The data of Slavonic languages, where both unanchoring devices cooccur, enable a coherent explanation of certain hitherto not fully understood phenomena in the domains of mood and aspect and shed a new light on the long-standing problem of the Romance so-called “factive” subjunctive.