Little is known about the effective elements of Interactive Cancer Communication Systems (ICCSs). A randomized trial explored which types of services of a multifaceted ICCS benefited patients and the nature of the benefit. Women with breast cancer (N=450) were randomized to different types of ICCS services or to a control condition that provided internet access. The Comprehensive Health Enhancement Support System (CHESS), served as the ICCS. ICCS services providing information and support, but not coaching such as cognitive behavior therapy, produced significant benefits in health information competence and emotional processing. Provision of Information and Support ICCS services significantly benefited women with breast cancer. More complex and interactive services designed to train the user had negligible effects.