The present research examines the role of two individual differences—mindfulness and neuroticism—in predicting acculturative anxiety forecasting error, above and beyond extraversion, agreeableness, conscientiousness, openness, emotional intelligence, and cultural intelligence. With 86 US undergraduate students who participated in study abroad programs, the current study provided three key findings. First, consistent with the claim of immune neglect, acculturative anxiety experienced abroad was lower than forecasted. Second, consistent with the claim that mindfulness reduces immune neglect whereas neuroticism increases immune neglect, mindfulness was negatively related to acculturative anxiety forecasting error, interestingly, only when the cultural distance between the host country and the USA was small, whereas neuroticism was positively related to acculturative anxiety forecasting error, regardless of the cultural distance. Third, parenthetically and consistent with a self-regulation view, mindfulness attenuated the relationship between neuroticism and acculturative anxiety forecasting error. These novel findings shed light on both mindfulness and affective forecasting research.