Circadian rhythms are integral biological processes that regulate multiple body (physiologic) functions through predictable oscillations on a 24-hour cycle. The timing of circadian rhythms is driven by a central clock located in the suprachiasmatic nucleus (SCN) within the hypothalamus of the brain, as well as regulating peripheral clocks that reside in virtually all organs and tissues outside of the brain. While circadian rhythms are endogenous, they can be entrained or synchronized to various environmental cues (e.g., shift work, jet lag, late-night eating, and exercise). Modern technology promotes a 24/7 society, where these environmental cues have been shown to affect an individual’s circadian alignment. Current evidence indicates that circadian misalignment is associated with several pervasive health consequences on both a cellular level and multiple organ systems level. Thus, understanding the consequences and their mechanisms is key in developing targeted therapeutic treatments. Traditionally, models of circadian misalignment have focused on evaluating central circadian rhythms, but evaluating peripheral circadian clocks will be essential to advance the understanding of circadian biology. The scope of this collection is to bring together a series of methods for assessing peripheral circadian rhythms in humans and animal models, through both genetic and environmental studies, which will further advance the discovery of the relevant mechanisms that drive the biologic consequences of circadian rhythm disruption.