We will randomly assign 303 women recently diagnosed with either breast or gynecological cancer and their partners to one of two conditions: (1) Seite an Seite, or (2) Treatment-As-Usual, in which couples receive no active psychosocial intervention. Assessment will be conducted pre-, post-, and at 6 and 12 months follow-up. These assessments include for both partners negative and positive self-report measures of individual functioning (such as mood, anxiety and benefit finding) and relationship functioning (such as relationship distress, communication patterns). Furthermore, at pre-, post- and 12-month Follow-up observational data on mutual supportive behavior when communicating about a cancer-related topic will be collected. The study may enhance our understanding of the significance of relationship skills in the process of adjusting to cancer as a couple and as an individual.