Abstract Based on a corpus study of 2074 occurrences in Archaic (424) and Classical (1650) Greek, I offer a unified explanation for the temporal reference extensions of counterfactual mood forms in declarative, interrogative, wish and de-activated illocutions (i.e. subordinate clauses). I propose a diachronic trajectory (life cycle) for counterfactual mood forms from past to present and future reference. Extensions are constrained diachronically by grammatical aspect (e.g. imperfect facilitating extensions to present reference more than the aorist or pluperfect), and actionality of the state of affairs in clausal context (atelic states of affairs enabling temporal extensions), as well as synchronically by illocutionary usage, collocations with temporal adverbs and common ground knowledge (i.e. temporal location known or not). This trajectory explains the replacements of the inherited counterfactual optative by the counterfactual indicative, because their life cycles are interlocked: in Archaic Greek the counterfactual optative had already extended from its original past to present and future reference and is losing its counterfactuality, whereas the counterfactual indicative referred only to the past and sometimes the present. In Classical Greek, temporal extensions of the counterfactual indicative are continued across different aspects, clause types and illocutions at different rates of change and the counterfactual optative is filtered out of the system.