In this paper, we use data from temporal, conditional, and coordinate constructions in Polish and Serbian to establish basic formal and semantic parameters defining conditional meaning in the two languages. Relying on the mental spaces analysis of conditional constructions in English (Dancygier and Sweetser 2005), we describe relative salience of different constructional parameters in Polish and Serbian. Specifically, we establish, through an analysis of a broad range of conjunctions and verb forms, that, similarly to English, predictive meaning is central to conditionality in both Polish and Serbian. However, in contrast to English, the Slavic languages under scrutiny rely to a lesser degree on specific conditional conjunctions and on clause order iconicity, and in fact favor different parameters (e.g., tense, mood, and aspectual forms, or overt markers of sequentiality) as central to predictiveness at a constructional level. At the same time, compositional mechanisms which are responsible for the emergence of predictive conditional meanings, even in absence of overt markers of conditionality, remain very similar to English, thus giving support to the general concept of constructional compositionality. (Barbara Dancygier and Radoslava Trnava)