Given the extensive literature surrounding deception detection and the behavioural cues indicative of lying, much less is known about the individual differences in successful truth-telling and lying ability. This is surprising given the potential benefits of identifying individuals in which effective lying ability is required for specific job roles (e.g., undercover police officers, politicians, military leaders, lawyers, professional gamblers; Semrad et al., 2019), and the implications of credibility judgements for witnesses and suspects in the legal arena. The current thesis proposed that one potential underlying cognitive mechanism involved in the ability to appear credible when telling the truth and lying is Episodic Future Thought (i.e., the ability to mentally simulate future personal events; Szpunar, 2010; EFT). Across three studies we assessed whether EFT ability affects credibility judgements when individuals tell the truth and lie about future events as well as current events. We also explored whether the EFT ability and credibility relationship was affected by presentation modality (spoken/written/sketches). Finally, we examined whether the EFT ability of the sender affected participants subjective cue use when judging credibility. In Study 1, participants EFT ability was measured and participants performed a truthful task and deceptive task (Exp. 1a). Supporting the prediction, verbal statements provided by individuals with higher EFT ability showed characteristics associated with credibility (i.e., statement length and level of detail) to a greater extent than those with lower EFT ability. Higher EFT individuals were also judged as more truthful in their spoken deceptive (but not truthful) statements (Exp. 1b). Supporting our predictions, participants with higher EFT ability also provided longer and more detailed written statements than those with lower EFT ability (Exp. 2a), and higher EFT participants’ truthful and deceptive written statements were also judged as more credible than lower EFT participants (Exp. 2b). Study 2 tested the prediction that the EFT ability of the sender will affect participants subjective cue use when judging the credibility of spoken and written statements. Supporting our hypotheses, EFT ability affected subjective cue use in spoken statements (Exp. 1) and written statements (Exp. 2). Based on the EFT and credibility findings from Study 1 and Study 2, in Study 3 we assessed whether the EFT ability and credibility relationship was found when participants described a truthful and deceptive current event (their occupation; in comparison to a future event in Study 1). Participants told the truth and lied about their occupation in a series of interviews. During the occupation interviews participants were asked to verbally describe the layout of their workplaces as well as sketch their workplace layout. As predicted, higher EFT individuals provided longer, more detailed, and more plausible verbal workplace layout descriptions, as well more plausible sketches (Exp. 1). However conflicting with our predictions, the EFT ability of the sender did not affect credibility judgements of the verbal descriptions (Exp. 2), or sketches (Exp. 3). In summary, EFT ability affected the ability to generate credible future and current events across modalities (spoken/written/sketched). Furthermore, EFT ability affected credibility judgements of future but not current events. A possible explanation for these findings is that EFT ability is an underlying cognitive mechanism relating to credibility when describing future specific events (i.e., intentions) rather than a general simulation ability unaffected by the temporal direction of the told truth/lie. This thesis contributes to the fields of individual differences in truth and lie telling ability and true and false intentions. It also makes a novel contribution to the field of EFT, proposing that in addition to the functional benefits of EFT (e.g., decision making, problem solving, emotion regulation, goal processing, implementation intentions, and planning, Schacter et al, 2017; Spuznar, 2010), EFT may also be involved in truth telling and lying behaviour.