Inflammation is a robust and reliable predictor of all-cause mortality in older adults (1). Proinflammatory cytokines such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) play a role in cardiovascular disease, type II diabetes, arthritis, osteoporosis, Alzheimer’s disease, periodontal disease, and frailty and functional decline (2–3). In addition, inflammation is now regarded as a risk factor for most cancers because of the evidence that inflammation influences tumor promotion, survival, proliferation, invasion, angiogenesis, and metastases (4). Behavioral lifestyle factors can substantially influence inflammation. Obesity has been characterized as a state of chronic inflammation because of the elevated plasma levels of IL-6, TNF-α, and CRP (5). One obvious mechanism is provided by the fact that adipocytes (fat cells) are capable of producing and secreting IL-6 and TNF-α; in fact, up to 30% of IL-6 may be derived from adipose tissue (6). Physical activity is also an important behavioral cofactor; people who describe themselves as active have lower levels of inflammatory biomarkers than their sedentary counterparts (7). Indeed, when physical or cardiorespiratory fitness is assessed rigorously and objectively by maximal exercise testing, fitness is inversely associated with inflammation, even after adjusting for confounds including age, smoking, medications, and visceral fat (8–11). Although regular physical activity is associated with lower levels of IL-6 and other proinflammatory cytokines, acute exercise transiently boosts production and release of IL-6 from skeletal muscles; the IL-6 that is released during physical activity inhibits TNF-α production and can induce IL-10 production, one mechanism underlying exercise’s anti-inflammatory function (1). Lower levels of circulating IL-6 at rest as well as following exercise appear to be the normal adaptation to training (12) In addition to exercise and obesity, behavior affects inflammation through other pathways; even relatively modest levels of anxiety and depressive symptoms can raise proinflammatory cytokine production (13). Additionally, psychological stressors can directly provoke transient increases in proinflammatory cytokines (14–15), and chronic stressors have been linked to sustained overproduction of IL-6 (16–17). Yoga’s reputation for stress reduction and mental health benefits has bolstered its popularity in recent years, and data from randomized trials suggest that yoga reduces symptoms of anxiety and depression (18–19). Hatha yoga, the most common form practiced in the western world, combines body postures or asanas, breath control or pranayama, and meditation (20). Mechanistic explanations for yoga’s potential mental and physical health benefits have highlighted reductions in sympathetic nervous system tone (21–22), and increases in vagal activity (22), both of which could have favorable endocrine and immune consequences, including lower inflammation. In fact, one recent randomized trial suggested that yoga might have positive benefits for inflammation; 9 heart failure patients randomized to a two-month hatha yoga intervention showed a 22% reduction in IL-6 and a 20% reduction in CRP compared to minimal change in the 10 patients who received standard medical care (23). In contrast, CRP did not change following a 6-week nonrandomized trial in 33 individuals both with and without established coronary artery disease, but the group did show significant reductions in blood pressure, heart rate, and body mass index (BMI) (24). Surprisingly few studies have attempted to relate endocrine or immune function to yoga practice, even though some hatha yoga postures are characterized as immune enhancing or restorative (25). We assessed cardiovascular, inflammatory, and endocrine responses in novice and expert yoga practitioners before, during, and after a hatha yoga session, as well as in two control conditions. To test yoga's restorative potential, stressors preceded each of the three conditions, providing data on the extent to which yoga speeded an individual's physiological recovery. In addition, tape stripping a small area of forearm skin before each of the conditions provided data on the course of skin barrier repair, a stress-sensitive process modulated by both cortisol and cytokine production (26–27). The ability to minimize autonomic and inflammatory responses in stressful situations undoubtedly influences the burden that stressors place on an individual. Thus, we designed this study to assess yoga’s ability to promote recovery from a stressor. We elected to conduct the yoga session after the stressor, rather than prior to the stressor, for several reasons. First, anticipation of a stressor following the yoga session could reduce participants’ ability to fully relax and concentrate during the yoga session, particularly among novices; completing the stressor prior to the yoga session could allow for a more relaxing yoga experience, providing greater power to detect effects of yoga. In addition, our ability to track changes in physiological markers of interest during the yoga session was improved by eliciting a physiological response prior to the session. Finally, using a stressor prior to the yoga session allowed us to examine whether regular yoga practice resulted in differential magnitude of reactivity to the stressor, independent of the effects of a recent yoga session. We hypothesized that: (1) experienced yoga practitioners would have lower levels of inflammation, and smaller autonomic, endocrine, and inflammatory responses to the stressors than novices. (2) During and following the yoga session, subjects would demonstrate more rapid declines (recovery) in stress hormones and proinflammatory cytokine production, and better skin barrier repair than evidenced following either of the control conditions. Mood measures would reflect greater positive change following yoga compared to the control conditions.