The aim of this study was to identify emotion regulation (ER) strategies that most strongly impact momentary mood in a sample of 23 adults with and 19 without autism spectrum disorder (ASD). Participants completed cognitive and behavioural assessments, online questionnaires, and experience sampling methodology questions. In the ASD group, the use of dampening and other-blame reduced mood while savouring and emotional acceptance improved mood. The use of self-blame and avoidance negatively impacted mood only in the non-ASD group, suggesting the use of these two strategies do not reduce mood in individuals with ASD. ER and mental health interventions should capture ER strategy use and aim to decrease maladaptive strategy use and increase adaptive strategy use.