Background: Family caregivers are confronted with high demands creating a need for professional support and at the same time hindering its utilization. Telephone support allows easier access than face-to-face support because there is no need to leave the person with dementia alone or find an alternative carer. It is also independent of transport possibilities or mobility. The objectives are to evaluate whether telephone-based cognitive-behavioral therapy, which is implemented in established care provision structures, improves outcomes compared to usual care and whether it is as effective as face-to-face cognitive-behavioral therapy. Methods/Design: If participants live in the area of one of the study centers (Jena, Berlin, Munich) and indicate that attendance of a face-to-face therapy is possible, they will be assigned to the face-to-face group. The other participants will be randomized to receive either telephone-based cognitive-behavioral therapy or usual care. Data will be collected at baseline, post-intervention, and at a 6-month follow-up. The primary outcomes will be depressiveness, burden of care, health complaints, and problem-solving ability. The secondary outcomes will be anxiety, quality of life, violence in caregiving, utilization of professional assistance, and cost effectiveness. Discussion: This paper describes the evaluation design of our telephone-based cognitive-behavioral therapy in a randomized controlled trial. If this intervention proves to be an effective tool to improve outcomes, it will be made accessible to the public and the use of this support service will be recommended.