Smartphones and wearables have made in-vivo assessment of stress, coping, and emotion via intensive longitudinal designs (ILDs) especially appealing. In this chapter, we briefly address the usefulness of adding an ILD framework to the coping researcher’s toolbox in the quest to gain a comprehensive and developmentally informed understanding of adolescent coping. Their importance rests on the ability of ILDs to capture coping microprocesses. Next, we draw on data to answer a pertinent question related to popular approaches to assessing coping via ILD: whether delivering ILD surveys via phone calls or text messages to adolescents reveals differences in compliance and data quality. We follow this with a discussion of several challenges associated with implementing ILDs, including types of coping questions these methods are less well-suited to address. We highlight the need to match theory to methods, and the need for a priori consideration of analytic approaches. This section further points to useful published resources for making optimal use of ILDs in developmental coping research, as well as describes novel passive sensing methods and physiological measurement approaches available via smartphones and wearables. We conclude the chapter with a brief discussion of how ILDs complement traditional longitudinal examinations of coping development.