The Pediatric Health, Affect and Biobehavioral (PHAB) research lab examines the interconnections between affect, related biobehavioral processes (including nonvolitional and volitional self-regulatory systems), and health in youths and young adults with or at-risk for chronic and complex medical conditions (e.g., type 1 diabetes, overweight/obesity, substance use). We use an interdisciplinary approach and complex methodology, such as daily diary, ecological momentary, and psychophysiological assessment procedures, to answer questions about how to promote optimal pediatric health in real-time and at the trait level. We also emphasize the impact of sociocultural functioning on health and development; thus, we often explore the relationships between key study variables at the individual level as well as within dyads (e.g., parent-child dyads) and examine the translation of findings across diverse populations. Our goal is to develop and test mobile health interventions that target the key mechanisms identified in initial pilot studies.