Participation or involvement in everyday occupations is vital for all humans. As described by the World Health Organization, participation has a positive influence on health and well-being. The presence of disability has been found to lead to participation that is less diverse, is located more in the home, involves fewer social relationships, and includes less active recreation. Occupational therapy is in a unique position to contribute to the development and fulfillment of participation for persons with and without disabilities. This article describes the nature and outcomes of participation. Characteristics to define and measure meaningful participation are outlined. Information about time use will help to develop an understanding of patterns of participation across locations, gender, culture, and the life span. Factors that affect participation within the environment, family, and persons are summarized. Occupational therapy research is needed to examine the complex relationship among person, environment, and participation in occupations. In practice and education, knowledge about participation can enhance the client-centered and evidence-based nature of occupational therapy services.