Mindfulness is an integrative, mind-body based approach that helps people change the way they think and feel about their experiences. It is a way of paying attention to the present moment by using meditation, breathing techniques, and yoga. Mindfulness involves consciously bringing awareness to thoughts and feelings, without making judgments , allowing the individual to become less enmeshed and better able to manage them. The objective of this review is to summarize the clinical effectiveness and guidelines for the use of mindfulness interventions for the treatment of post-traumatic stress disorder (PTSD), generalized anxiety disorder (GAD), depression, and substance use disorders in adults.