This article reviews the use of ecological momentary assessment (EMA) and ecological momentary intervention (EMI) in clinical research applications. EMA refers to a method of data collection that attempts to capture respondents' activities, emotions, and thoughts in the moment, in their natural environment. It typically uses prompts administered through a personal electronic device, such as a smartphone or tablet. EMI extends this technique and includes the use of microlevel interventions administered through personal electronic devices. These technological developments hold promise for enhancing psychological treatments by prompting the patient outside of therapy sessions in his or her day-to-day environment. Research suggests that EMI may be beneficial to participants and that this effect is amplified when EMI is delivered in the context of ongoing psychotherapy. EMI may reflect a cost-effective mechanism to enhance therapeutic outcomes.