The ability to think about the future--prospection--is central to many aspects of human cognition and behavior, from planning and decision making, to self-control and the construction of a sense of identity. Yet, the exact nature of the representational systems underlying prospection is not fully understood. Recent findings point to the critical role of episodic memory in imagining specific future events, but it is unlikely that prospection depends solely on this system. Using an event-cueing paradigm in two studies, we here show that specific events that people imagine might happen in their personal future are commonly embedded in broader event sequences--termed event clusters--that link a set of envisioned events according to causal and thematic relations. These findings provide novel evidence that prospection relies on multiple representational systems, with general autobiographical knowledge structures providing a frame that organizes imagined events in overarching event sequences. The results further suggest that knowledge about personal goals plays an important role in structuring these event sequences, especially for the distant future. (Contains 2 tables and 2 figures.)