This study focuses on the under-researched subject of “state authenticity”, the experience of expressing one’s true self. The 2 major hypotheses of the causes of state authenticity are tested: behavioural content versus consistency with personal traits. Investigations examine the proposal that behaviour expressing values, specifically “helping others” increases state authenticity, regardless of an individual’s own helpfulness-traits. Using a web-based survey, 238 participants were randomly assigned to a helping or non-helping condition and immediately thereafter reported their state authenticity. To test the possibility that reports of state authenticity are affected by timing, 2 weeks later participants retrospectively reported their previous authenticity. Contrary to expectations, no significant differences were found between helpers’ and non-helpers’ state authenticity at the time of the helping. However, both conditions reported increased recalled authenticity, with helpers reporting greater increases than non-helpers for the recalled true self and authentic living. Helpers’ increased authenticity was associated with behavioural content rather than traits. Discussions cover the possibility of classes of authenticity with differing needs for reflection, while the relevance of behavioural content to authenticity is considered in terms of adaptive functionality. Alternative interpretations cannot be ruled out and suggestions for future work are included.