Authenticity has recently been identified as a state as well as a stable trait, with state authenticity dependent on the demands of the situation. Certain situations cause individuals to feel less authentic, namely situations where behaviour is unnatural. We looked at the process of self-regulation and its effect on state authenticity. Self-regulation involves controlling and inhibiting behaviour and this type of behaviour may be defined by situational factors. This effect was examined using an emotion regulation paradigm with participants aged 18 – 36. The present study found that emotion regulation did cause participants to feel a reduced sense of authenticity. Discussion focuses on the implications for regular suppression of emotions, and on the indirect effect of emotion regulation on the levels of healthy psychological functioning associated with authentic behaviour.