This work investigates how we process and represent event duration in on-line language comprehension. Specifically, it examines how events of different duration are processed and what type of knowledge underlies their representations. Studies 1-4 examined verbs and phrases in different contexts. They showed that durative events took longer to process than non-durative events and that the duration attributed to the stimulus events correlated with on-line processing times. Studies 5 and 6 indicated that durative events occur in semantically more diverse contexts and elicit semantically more diverse associations than non-durative events. Semantic and contextual diversity also correlated with attributed durations and processing times. Results indicate that (a) event-specific durations are computed on-line from multiple unfolding cues, (b) processing cost and duration representations emerge from semantic and contextual diversity reflecting our experience, and (c) key components of duration representations may be situation-specific knowledge of causal and contingency relations between events.