Episodic memory enables individuals to recollect past events as well as imagine possible future scenarios. Although the episodic specificity of past events declines as people grow older, it is unknown whether the same is true for future events. In an adapted version of the Autobiographical Interview, young and older participants generated past and future events. Transcriptions were segmented into distinct details that were classified as either internal (episodic) or external. Older adults generated fewer internal details than younger adults for past events, a result replicating previous findings; more important, we show that this deficit extends to future events. Furthermore, the number of internal details and the number of external details both showed correlations between past and future events. Finally, the number of internal details generated by older adults correlated with their relational memory abilities, a finding consistent with the constructive-episodic-simulation hypothesis, which holds that simulation of future episodes requires a system that can flexibly recombine details from past events into novel scenarios.