There are 13.7 million cancer survivors in the United States. By 2050 the rate of growth for cancer survivors is expected to outpace the rate of growth for incident cancer cases. Approximately 70 percent of cancer survivors have co-morbid conditions that require a comprehensive approach to their medical care. Yet, cancer survivors do not receive recommended follow-up care at appropriate levels, with regard to both needed preventive care and chronic disease management. Survivors may benefit from psychosocial tools and support to help them cope with care transitions, to appropriately monitor their health, and to help them manage their interactions with members of the healthcare provider team. Unfortunately, there is currently a lack of psychosocial tools designed specifically to help survivors proactively manage their healthcare from the termination of treatment into extended survivorship. To fill this void, we draw on the social and behavioral science evidence base in social interaction and health communication to develop and test a highly innovative, self-management intervention: Extended Cancer Education for Longer-term Survivors (EXCELS). Based on health communication best practices, as well as on smart technology for ready access to patients, the EXCELS intervention will consist of (1) enhanced education and decision support materials delivered via mobile web and smart phone application and (2) health coaching engagement. The plan for intervention development involves three steps: first, during the formative phase, we will use qualitative methods (i.e., focus groups with survivors, depth interviews with primary care healthcare team members, user testing) to inform the design and iterative development of EXCELS. Second, we will pilot the intervention using a randomized controlled trial study design. Specifically, we will enroll 480 cancer survivors (breast, prostate, colorectal) who have completed active cancer treatment at least 2 years ago. The comprehensive EXCELS intervention consists of an ongoing 12 month intervention that entails (1) enhanced education and self-care support materials delivered via mobile web/smart phone application and (2) health coaching calls. A 2X2 factorial design will be used to test "proof of concept" or efficacy for the fully implemented EXCELS intervention compared with usual care so that the combined intervention - as well as each individual component - will be tested. The primary outcomes are use of preventive health services and tracking of cancer recurrence and late effects with patient coping as a secondary outcome. Outcomes will be assessed at baseline and at 6, 12, and 18 months by telephone interviews and chart audit by blinded research staff. Finally, a process evaluation of intervention implementation, as well as pilot data from this study, will be used to refine the intervention for testing in a larger implementation and dissemination research study.