This systematic review and meta-analysis evaluates the efficacy of meditation programs in reducing psychological stress and improving well-being in diverse adult clinical populations. The study included 47 randomized trials with 3,320 participants, focusing on mindfulness meditation programs and comparing them to active controls. Mindfulness meditation programs showed moderate evidence of improving anxiety, depression, and pain, with low evidence of improving stress/distress and mental health-related quality of life. Mantra meditation programs had low evidence of no effect on any outcome. Meditation programs did not show significant effects on positive mood, attention, sleep, weight, or health-related behaviors affected by stress when compared to specific active controls. The review suggests that meditation programs can reduce negative dimensions of psychological stress, particularly anxiety, depression, and pain, but more research is needed to confirm these findings and explore their effects on positive dimensions of mental health and stress-related behaviors.This systematic review and meta-analysis evaluates the efficacy of meditation programs in reducing psychological stress and improving well-being in diverse adult clinical populations. The study included 47 randomized trials with 3,320 participants, focusing on mindfulness meditation programs and comparing them to active controls. Mindfulness meditation programs showed moderate evidence of improving anxiety, depression, and pain, with low evidence of improving stress/distress and mental health-related quality of life. Mantra meditation programs had low evidence of no effect on any outcome. Meditation programs did not show significant effects on positive mood, attention, sleep, weight, or health-related behaviors affected by stress when compared to specific active controls. The review suggests that meditation programs can reduce negative dimensions of psychological stress, particularly anxiety, depression, and pain, but more research is needed to confirm these findings and explore their effects on positive dimensions of mental health and stress-related behaviors.