With an increasing multicultural aging population in the U.S., depressive symptoms in midlife racial/ethnic minorities are becoming increasingly significant. The prevalence of depression among Asian Americans is about 4.5 times higher than that of Americans in general. Within the Asian- American demographic, Korean Americans have the highest rate of depression. Within the Korean-American group, midlife Korean-American women are at increased risk of depressive symptoms because of their gender and age. Furthermore, the recent COVID19 pandemic has placed additional stress to this specific population. Korean Americans have a cultural preference for natural lifestyle management strategies (e.g., promotion of lifestyle physical activity) for depression as opposed to pharmacotherapy, and there is a cultural emphasis on one’s ability to handle stresses without outside assistance. A technology-based program using a web app could provide a highly innovative and effective way to promote lifestyle physical activity and improve depressive symptoms experienced by this specific population in a manner that appeals to their cultural preference. Yet, few programs are available for this specific population and little is known about the efficacy of technology-based interventions in improving depressive symptoms of racial/ethnic minority women including this population. Based on Preliminary Studies, the research team has developed and pilot-tested the Web-App based Lifestyle Physical Activity Promotion Program in improving depressive symptom experience of midlife Korean American women (WPAPP-K). WPAPP-K has several unique features that overcome the shortcomings of existing programs such as surface and deep cultural tailoring and social media functions. The purpose of this randomized intervention study is to determine the efficacy of WPAPP-K in improving depressive symptom experience of midlife Korean American women. The specific aims are to: (a) determine whether the intervention group will show significantly greater improvements than the control group in self-reported depressive symptom experience from a pre-test (T0) to post 6-months (T1) and post 12-months (T2); (b) determine whether the intervention group will show significantly greater improvements than the control group in self-reported lifestyle physical activity experience from T0 to T1 and T2; (c) identify whether physical activity experience mediates the intervention effects of the WPAPP-K on depressive symptom experience from T0 to T2; and (d) determine whether the effects of WPAPP-K on depressive symptom experience are moderated by selected factors. The study is theoretically guided by the Bandura’s Theory of Behavioral Change and the Stress and Coping framework by Lazarus and Folkman. The study adopts a randomized repeated measures pretest/posttest control group design among 300 midlife Korean American women who are nationally recruited. The long-term goals are to: (a) implement the program in various pr...