Background: Patients with mild cognitive impairment (MCI) have to deal with an uncertain prognosis and also face a multitude of memory-related problems and psychosocial consequences. A newly developed group programme proved to be feasible, however, it needed confirmation by a controlled study. Aim: This controlled study evaluates this group therapy for MCI patients aimed to help them accept and manage the memory problems and the psychosocial consequences. The programme combines elements from psychoeducation, cognitive rehabilitation and cognitive-behavioural therapy. Patients and Methods: Ninety-three MCI patients received treatment, with 30 patients being first assigned to a waiting list, thus serving as their own control group. Pre- and post-treatment acceptance and helplessness were assessed using subscales of the Illness Cognition Questionnaire, while distress and general well-being were gauged with the Geriatric Depression Scale and subscales of the RAND-36. Results: Linear mixed model analyses showed that, relative to the controls, acceptance had increased more in the intervention group compared to the waiting-list period (p = 0.034). Distress and general well-being showed no changes. Treatment responders demonstrating a clinically significant effect on acceptance and two of three secondary outcome measures had higher baseline levels of helplessness and fewer self-reported memory complaints in daily life than patients who did not improve. Conclusion: The intervention helped the patients deal better with their uncertain future in that they were overall better able to accept their condition, with especially the female patients showing a decrease in helplessness cognitions, although the effects were relatively small.