Users of Slavonic languages, and arguably of Old Church Slavonic, have in certain circumstances the luxury of a choice between two types of present tense. The distinction between them is contingent on a system of aspectual contrasts different from those found in western European languages. Verbal aspect in the Slavonic languages:

• • involves a semantic contrast between a situation, characterized as a state or as ongoing activity (imperfective), and a situation-changing event (perfective);

• • applies to each verb, which has the same aspect in all its forms irrespective of tense and mood;

• • may be formally unmarked, implicit in verbal meaning, but more often is associated with derivational morphology of three kinds:

  • i. prefixation, which may produce (a) perfective lexical derivatives; (b) perfective Aktionsarten; (c) pure perfectives; (d) imperfective lexical derivatives; (e) in Czech and some varieties of Serbian or Croatian, future forms of imperfective verbs;

  • ii. suffixation, productive of perfectives but also found in imperfectives;

  • iii. suffixation, productive of secondary imperfectives derived from perfective lexical derivatives and Aktionsarten. This is the most reliable morphological indicator of aspect. A secondary imperfective may denote a situation in which the action expressed by the related perfective (a) occurs repeatedly, or (b) is presented as ongoing activity, or (c) is conveyed in the historic present.

• • is predictably imperfective in verbs governed by phasals.

• • tends to be correlated with tense, but not entirely predictably. In particular:

  • i. the non-past imperfective is required for the immediate present of the moment of speech, and tends to be used as an iterative and for the historic present; but it may compete with the non-past perfective in the latter two functions;

  • ii. the non-past perfective is mostly specialized to future use in West and East Slavonic languages, where it contrasts with a periphrastic imperfective future; but it is also used as an historic present, especially in Czech and in South Slavonic Croatian, Serbian and Slovene, and more generally as a non-actual present in the South Slavonic languages, where a different periphrastic future admits both aspects.