The environment has been found to be a major contributor to data variability and many aspects of the laboratory environment are stressful to rodents and do not accurately reflect the human experience. Thermal stress from normal laboratory temperatures reduces immune function, breeding performance, and alters behavior; lighting may be too intense, increasing stress, and lead to immune suppression; noise from ventilators, construction, or ultrasonic noise from monitors can affect breeding performance and stress hormones; cage changing disrupts odor cues that can cause stress and increase aggression and suppress immune function. Chronic uncontrollable stress is widely acknowledged for its negative alterations to physiology, yet, there is a significant gap in the understanding of how the laboratory environment affects mouse physiology and behavior, in particular, as it relates to characteristics of the human disease being modeled. This presentation will provide attendees with information on known causes of stress in common mouse vivariums and how it can be reduced by small changes including environmental enrichment.