Objectives. To determine whether the Active Living Every Day (ALED-I) internet-delivered theory-based physical activity (PA) behavior change program increases PA and improves cardiometabolic disease risk factors (CDRF) in sedentary overweight adults.Methods. The study was a randomized control trial that took place in southern Wyoming and northern Colorado from 2005–2007. Thirty-two men and women (21–65 years) were randomized to a 16-week ALED-I intervention (n=14; age=41.4±3.7 years; BMI=32.3±1.3 kg/m 2 ) or a delayed intent-to-treat control condition (n=18; age=49.4±1.7 years; BMI=30.6±0.8 kg/m 2 ). At baseline and post-intervention, PA by pedometer and CDRFs were measured.Results. Both groups had similar baseline PA levels. ALED-I increased PA by an average of 1384 steps/day (p=0.03) compared to 816 steps/day (p=0.14) for the control group. Waist circumference (100.6±2.4 vs. 96.6±2.7 cm) and Coronary Risk Ratio (5.1±0.3 vs. 4.7±0.3) decreased in the ALED-I group and did not change in the control group (99.2±2.2 vs.99.8±2.1 cm) and (3.7±0.1 vs. 3.7±0.1), respectively.Conclusions. The internet-delivered ALED program increased PA and improved some CDRFs in sedentary overweight/obese adults. To our knowledge, this is the first efficacy trial of the internet-delivered ALED program. Further studies are warranted due to the reach and cost-effectiveness of internet-delivered PA programs.