ABSTRACTBackground: A growing body of research has examined the intersection of mindfulness and substance use, and a large body of research has examined the relation between mindfulness and anxiety. Unfortunately, no research has been conducted on the relation between mindfulness and anxiety symptoms among young adults (i.e., 18–25 years old) in treatment for substance use. The purpose of the current study was to examine the relation between one facet of mindfulness, moment-to-moment attention, and anxiety (panic and generalized anxiety) among young adults in treatment for substance use. Methods: Preexisting patient records from a residential substance use treatment center for young adults were reviewed (N = 148). Patient records were examined from May 2012 to August 2013, which represented all young adult patients admitted to the residential treatment facility during this time. Results: Findings demonstrated that moment-to-moment mindful attention was associated with symptoms of panic disorder and generalized anxiety disorder even after controlling for gender, age, education, alcohol use, drug use, and the shared variance in generalized and panic symptoms. There were no gender differences in moment-to-moment mindful attention. Conclusions: These findings provide preliminary evidence that moment-to-moment mindful attention is associated with panic and generalized anxiety in young adults in substance use treatment. Combined with previous research on mindfulness-based interventions among adults in substance use treatment, research should examine the efficacy of mindfulness-based interventions for young adults in substance use treatment.