Measured oxygen consumption, tidal volume, respiration rate, heart rate, systolic and diastolic blood pressure before the Ss (N = 39) learned Transcendental Meditation (TM: N = 21) or Jacobson's Progressive Relaxation (PR: N = 18). Ss were tested immediately after learning either technique and again 5, 10, and 15 weeks later. While there were no significant differences between groups for any of the physiological variables at pretest, the TM group displayed more significant decreases during meditation and during activity than did the PR group. Both groups displayed significantly lowered metabolic rates during TM or PR. The generally more significant and comprehensive results for mediators were explained primarily in terms of the greater amount of time the TM group spent on their technique, plus the differences in the two techniques themselves. Several avenues for future research are discussed.