There is a pressing need for research on behavioral interventions capable of being translated into practice for the self-management of diabetes and other chronic illnesses. The vast majority of diabetes self-management research has been conducted in academic settings, and has not addressed real world application issues or the challenges and context of primary care practice. It is well-documented that preventive care provided to diabetes patients is suboptimal, and that most patients are especially in need of assistance with behavior- change aspects of diabetes self-management. Based on the current literature, theory, and lessons from our previous efficacy research, this competing renewal application will address these issues by refining and experimentally evaluating a practical, computer-based (combined Internet and automated telephone) diabetes self-management intervention For primary care patients. The intervention is designed to facilitate dietary and physical activity practices, medication-taking, and patient activation around diabetes care. A total of 425 type 2 diabetes patients from primary care providers in HMO and mixed-payer settings will be randomly assigned to one of three conditions in an effectiveness study: (1) enhanced usual care;(2) a second generation version of our social-ecological, theory- based behavioral intervention to maximize linkage with primary care and community resources, plus enhanced interpersonal support;or (3) an entirely automated version of this intervention. The two active interventions will each include several innovative components to address reach, low health literacy, change in multiple health behaviors, continued participant involvement overtime, social environmental support, and maintenance/relapse prevention strategies. Evaluation will be comprehensive and based on the RE-AIM model dimensions of reach, effectiveness, adoption, implementation, and maintenance. We will employ new metrics to address issues such as health disparities, any adverse effects, and implementation costs. Key outcomes will include behavior change (dietary, physical activity, and medication-taking) and the UKPDS multiple risk formula that combines several heart disease risk factors (HbA1c, blood pressure, smoking, and lipids). We will include a sophisticated cost and cost- effectiveness analysis. Key secondary outcomes and process measures will include diabetes-specific quality of life, patient activation, and perceived social-environmental support at 6- and 12-month follow-ups. The results of such a practical effectiveness trial, conducted with a representative sample of primary care patients from heterogeneous practices, and emphasizing both internal and external validity criteria, has important implications both for the science of behavior change and for translating research to practice.