The National Diabetes Prevention Program (National DPP) was established by Congress in 2010, with a focus on disseminating the evidence-based Lifestyle Change Program (LCP). This 12-month program consists of 26 lessons covering various topics related to goal setting, tracking food and physical activity, motivation, and support groups. Many organizations, including Cooperative Extension (CE), have adopted this program. In the first study conducted by the Virginia Cooperative Extension (VCE), the outcomes of the prediabetes LCP were examined across different age groups and delivery modalities. It was found that distance learning LCPs had slightly higher enrollment levels compared to in-person programs (51% vs. 49%). Moreover, participants aged 60 and older had a significantly higher attendance rate in the distance learning program. The VCE LCP resulted in 49 participants (35%) achieving at least a 5% weight loss, with 29 of them being 60 years or older. When considering the program delivery method, a higher percentage of individuals enrolled in distance learning programs (53%) achieved at least a 5% weight loss. Additionally, 86 participants (62%) engaged in an average of 150 minutes of physical activity per week, with a higher percentage in the in-person programs (64%) and among those aged 60 and older (67%). In Study 2, the distance learning LCP implementation fidelity was evaluated across five states, along with its association with program outcomes. The evaluation tool assessed structural and instructional implementation components. The results indicated that certain structural components directly influenced increased physical activity among participants. Additionally, the coaches' preparedness for the sessions directly impacted participants' weight loss. In addition to implementation fidelity, age was identified as an independent factor affecting weight loss percentage and attendance. Overall, the findings from both studies underscore the significance of effective implementation fidelity to program design in achieving desired health outcomes. The LCP shows promise as an intervention for individuals at risk of developing type 2 diabetes and can be effectively implemented through both in-person and distance learning methods by Cooperative Extension programs nationwide. / Doctor of Philosophy / The prevalence of diabetes and prediabetes in the United States is a significant concern. The Centers for Disease Control (CDC) reported that around 34.2 million people in the U.S. have diabetes, with approximately 96 million adults having prediabetes in 2022. Lifestyle changes, such as increasing physical activity and losing weight, can reduce the risk of prediabetes progressing to diabetes. In response, the CDC established the National Diabetes Prevention Program (National DPP) in 2010, focusing on an evidence-based Lifestyle Change Program (LCP). The LCP is a 12-month program covering various topics and has been adopted by organizations like Cooperative Extension (CE). Two studies were conducted to assess the effectiveness and implementation of the LCP. The first study, carried out by the Virginia Cooperative Extension (VCE), compared outcomes of distance learning and in-person LCPs among adults of different ages. It found slightly higher enrollment levels in distance learning programs and observed a higher attendance rate among participants aged 60 and older in the distance learning program. The study showed that the VCE LCP resulted in a 35% weight loss for 49 participants, with 59% of them being 60 years or older. Distance learning programs also had higher success rates in achieving a 5% weight loss and 150 minutes of physical activity per week. The second study evaluated the implementation fidelity of the distance learning LCP conducted by Cooperative Extension in five states. It found that certain program components, both structural and instructional, directly influenced participants' physical activity levels. The preparedness of coaches for the sessions significantly impacted weight loss outcomes. In addition to implementation fidelity, age was identified as an independent factor affecting weight loss and attendance. Both studies underscore the importance of effective program implementation fidelity to program design in achieving desired health outcomes. The findings support the LCP as a promising intervention for individuals at risk of developing type 2 diabetes. It highlights its effectiveness through both in-person and distance learning methods implemented by Cooperative Extension programs nationwide.