This article explores recent progress in theory, research and practical applications of reminiscence. It first describes the evidence for reminiscence as a naturally occurring process, and discusses the different functions of reminiscence and their relationships with mental health and lifespan processes. Three basic types of reminiscence that relate to mental health are specified: conversations about autobiographical memories and the use of personal recollections to teach and inform others have social functions; positive functions for the self include the integration of memories into identity, recollections of past problem-solving behaviours, and the use of memories to prepare for one's own death; negative functions for the self are the use of past memories to reduce boredom, to revive bitterness, or to maintain intimacy with deceased persons. It is proposed that in interventions the three types are addressed differently: simple reminiscence stimulates social reminiscence and bonding and promotes positive feelings; life review uses the positive functions to enhance personal wellbeing; and life-review therapy seeks to reduce the negative uses and thereby alleviate symptoms of mental illness. Studies of the effectiveness of interventions have provided some evidence that interventions are effective in relation to their goals. The review closes with recommended directions for future reminiscence research.