Generalized Anxiety Disorder (GAD) is a chronic condition whose hallmark feature is excessive and uncontrollable worry (American Psychiatric Association, 2013). Theories of GAD propose that specific cognitive biases are involved in the maintenance and etiology of chronic worry. One cognitive bias that plays a role in worrying is abstract thinking, or the tendency to "verbalize" thoughts and worries in a manner that is vague and lacking in detail. There is evidence that training depressed people to think more concretely improves depressive symptoms and depression-type thinking styles, and reduces emotional reactivity. Given that chronic worry and depression have commonalities (e.g., repetitive thinking styles, difficulties with problem-solving and attentional control, emotion dysregulation), concreteness training may help people who struggle with chronic worry. The main goals of this proof of concept experiment are 1) to test in individuals reporting chronic worry the effects of an active form of concreteness training that involves imagery practice (compared to a no training control condition) on frequency of worrying, problem solving quality, and worry-related processes; 2) to examine the degree to which concreteness training causes improvements in daily worry and negative affect during the 7 days of practice. The study design will provide us with an understanding on a more "macro" level of the potential short-term benefits and will at the same time allow us to see, on a more "micro" level, how training concreteness affects worry and mood on a day-to-day basis during a 7-day period. The findings from this study will inform relevant clinical literature about efficacious methods to reduce chronic worry.