A 6-month home-based (HB) physical activity program was compared to a control (CTL) condition in terms of effect on physical activity and health-related fitness in three generations of women (daughter/ mother/maternal grandmother). Volunteers were randomly assigned to a HB or CTL condition. HB participants (n = 28) were asked to participate in lifestyle, aerobic, muscular strength, and flexibility activities at least 3 times per week and they completed 73% of the recommended PA bouts. CTL condition participants (n = 9) were asked to continue their usual pattern of physical activity. Changes in physical activity were measured pre-and post-intervention using the Physical Best questionnaire and pedometer step counts (3-day average). Changes in health-related fitness were assessed using Fitnessgram tests. Group x Time interactions were significant for changes in participation in flexibility activity (d/wk) and steps/day, indicating that the HB group experienced significant positive changes in the expected direction (+305% and +37%, respectively), while the CTL group regressed (-15% and -13%, respectively). The G x T interaction for mile time was significant, although not in the expected direction (CTL group < by 14% and HB group < by 5%). Findings should be interpreted with caution due to several limitations of the study, but several suggestions are made for more effectively studying this topic in the future.