David Horton Smith is Research and Emeritus Professor of Sociology at Boston College, USA, and an Honorary Visiting Professor at universities in the UK and Russia. The founder of ARNOVA and ICSERA, he won the Lifetime Achievement Award of ARNOVA in 1993. With a biography in the International Encyclopedia of Civil Society, Smith has written or edited many books and journal articles, including several encyclopedia entries.

Robert Stebbins is Professor Emeritus at the University of Calgary, Canada. His research and theoretic interests lie in work, leisure, and volunteering. His most recent books include Careers in Serious Leisure: From Dabbler to Devotee in Search of Fulfillment (Palgrave, 2014) and The Idea of Leisure ( 2012).

Jurgen Grotz is the Research Manager at the Institute for Volunteering Research, UK, and a Visiting Fellow at the School of Health Sciences, University of East Anglia, UK. He has over 25 years' research experience in the Voluntary and Community Sector, and has contributed to publications such as The State of the World's Volunteerism Report by UNV (2011).