AbstractThis study compared the psychological effects of Progressive Muscle Relaxation (PMR) and breathing exercises. Forty‐two students were divided randomly into two groups and taught PMR or breathing exercises. Both groups practiced for five weeks and were given the Smith Relaxation States Inventory before and after each session. As hypothesized, PMR practitioners displayed greater increments in relaxation states (R‐States) Physical Relaxation and Disengagement, while breathing practitioners displayed higher levels of R‐State Strength and Awareness. Slight differences emerged at Weeks 1 and 2; major differences emerged at Weeks 4 and 5. A delayed and potentially reinforcing aftereffect emerged for PMR only after five weeks of training—increased levels of Mental Quiet and Joy. Clinical and theoretical implications are discussed. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 1551–1557, 2001.