Background: Exercise is an evidence-based intervention for the management of chronic conditions, yet the majority of Veterans are inactive. Group telehealth (GT) delivered exercise can potentially improve access to and participation in exercise. GT exercise sessions may increase exercise participation by providing social support, but a better understanding of the feasibility and acceptability of this format is needed. Telehealth delivered exercise programs should be designed with initiation and maintenance phases, but there is not consensus regarding the strategies for delivering exercise maintenance interventions. Skills for exercise initiation and maintenance differ, and interventions that focus on one or the other are not likely to result in sustained exercise participation. Significance/Impact: As the Veterans Health Administration is the largest integrated health care system in the US, implementing successful exercise programs could have a profound impact of public health. National priorities including telehealth and access to care as well as management of chronic conditions will be addressed by the development of this GT exercise initiation and maintenance intervention. Innovation: GT exercise combines the benefits of group exercise sessions, such as social support, and telehealth technology. There have been no studies comparing GT exercise booster sessions plus text messaging to text messaging alone to support exercise maintenance. These two strategies will be used as a multi-faceted approach to improving exercise maintenance. Specific Aims: Aim 1: Adapt evidenced-based exercise components for a group telehealth (GT) exercise intervention, guided by stakeholder input. Using qualitative methods, I will explore the perspectives of stakeholders through focus groups and interviews. Intervention development will include an iterative approach and formative evaluation. Aim 2: Conduct a randomized pilot trial to assess the feasibility and acceptability of the GT exercise initiation and maintenance program. I will use lower extremity osteoarthritis (OA) as a model to conduct this work because: 1) lower extremity osteoarthritis (OA) is a prevalent condition among Veterans, 2) exercise is a first line recommendation for the management of lower extremity OA, and 3) I have previous experience in OA. Veterans with lower extremity OA (n=50) will be randomized to the intervention. I will assess feasibility (i.e. referral, retention, data collection) and acceptability (i.e. number of sessions attended, number of text message responses, participant and provider feedback). Aim 3: Determine contextual factors related to successful implementation and sustainability of telehealth- delivered exercise programs within VA. Gerofit, an existing telehealth-delivered VA exercise program implemented at multiple sites, will be used as a model. An explanatory sequential mixed methods design will be used to describe site characteristics and simultaneously explore the pers...