The proposed study will develop a Mindfulness Smartphone Intervention with Contingency Management (MSI-CM) for smoking cessation that can be readily available to depressed smokers receiving outpatient psychiatric treatment. The intervention will involve a series of brief mindfulness training that will be delivered via smartphone, that prompts patients to practice a mindfulness exercise multiple times a day while abstinent: 1) 10-days prior to their target quit date and 2) during the 2-week incentivized abstinence period (using CM) plus an additional 2 weeks (without CM) following their target quit date. We will use CM as an adjunct strategy to enhance the efficacy of mindfulness training due to its utility in producing short-term abstinence, so as to provide opportunities to practice mindfulness without smoking in one's natural environment. We will accomplish this objective by pursuing the following specific aims (in 2 phases):