PROJECT SUMMARY Smoking and depression frequently co-occur in pregnant women. Independently, both smoking and depression are associated with numerous adverse birth outcomes and negative impacts on infant and child health. Although the co-occurrence of depression in pregnant smokers has been noted in the literature, it has not been addressed in prenatal or postpartum smoking cessation intervention studies. Behavioral activation therapy (BA) has been found to be an effective treatment for depression in pregnant women. In the current study, we will adapt an existing BA protocol as a depression-focused intervention for depressed pregnant smokers. In the general population of smokers, there is accumulating evidence that extended courses of treatment with multiple counseling sessions result in significantly higher abstinence rates at long-term follow-up compared to standard treatment courses. The recent development of mobile/internet based software provides opportunities to deliver intensive, psychotherapeutic interventions via videoconferencing, which potentially increases the feasibility of providing such interventions to pregnant smokers across the prenatal and postpartum periods. Smartphone apps and supportive text messaging have been shown to be an effective adjunct for improving outcomes and increasing participant engagement in in-person psychotherapy treatments. However, the feasibility of providing psychotherapeutic videoconferencing plus supportive app messaging via smartphone has not yet been evaluated, nor is the feasibility of extending behavioral smoking cessation and depression treatments from the prenatal to postpartum periods known. In the current study, we will pilot test and evaluate the feasibility and acceptability of providing smartphone, videoconferencing-based BA treatment plus behavioral smoking cessation counseling, and a BA app (BA) to depressed pregnant smokers during the prenatal and postpartum periods; and will conduct a preliminary evaluation of BA’s effect on abstinence and depression at 6 months postpartum.