The circadian clock is composed of an endogenous oscillator which is regulated by environmental inputs which in turn drives the rhythmicity of molecular processes (e.g. gene expression over 24 hours) and corresponding physiological responses (e.g. leaf movement). In plants, the circadian clock regulates numerous physiological responses, including hormone signaling, metabolism, flowering time, hypocotyl elongation, and stress responses. The genetic variation found in circadian-related genes is often from wild species and landraces, highlighting the role of the circadian clock in crop domestication. While some is known about the role of circadian clock genes in model species, little is known about the circadian clock in most crops and about the impact of genetic variation on the clock. Potato is the fourth most produced food crop globally, accounting for nearly $4 billion in farm value within the U.S. We are investigating the circadian clock in potato and the role of the circadian clock in potato domestication and development through the use of genetic, genomic, cell/molecular biology, and bioinformatic techniques.