We aimed to determine whether group-based Cognitive Strategy Training (CST) for combat veterans with mild cognitive disorder and a history of traumatic brain injury (TBI) has significant posttreatment effects on self-reported compensatory strategy usage, functioning, and psychiatric symptoms. Participants included 21 veterans returning from conflicts in Iraq or Afghanistan with a diagnosis of Cognitive Disorder, Not Otherwise Specified and a history of combat-related TBI. Participants attended 6- to 8-week structured CST groups designed to provide them training in and practice with a variety of compensatory cognitive strategies, including day planner usage. Of the participants, 16 completed pre- and posttreatment assessment measures. Following CST, participants reported significantly increased use of compensatory cognitive strategies and day planners; an increased perception that these strategies were useful to them; increased life satisfaction; and decreased depressive, memory, and cognitive symptom severity. Group-based CST is a promising intervention for veterans with mild cognitive disorder, and randomized controlled trials are required to further evaluate its efficacy.