Mental time travel is the ability to mentally relive events in one's own past (episodic recall) and pre-live potential personal future events (episodic foresight). Recent research has used experience sampling to reveal when and how often we think about the past and future in everyday life; however, it remains unclear how much of thought is episodic, involving the sense of self that underpins mental time travel. In this study, we investigate the use of experience sampling to assess the frequency of episodic past and future thought in everyday life. Participants (n=214) were exposed to 20 short message service prompts over 1 or 2days. Half of thoughts were sited in the present; of the remainder, future-oriented thoughts were more frequent than past-oriented thoughts. Participants reported 20% of thoughts as episodic. This study suggests that experience sampling methodology can provide a means of assessing episodic thought during everyday activities.