Background: The Cochrane Collaboration encourages wide participation in its work and seeks to reduce barriers to participation by a diverse range of individuals. Contributors include volunteers and paid staff. To what extent are Cochrane reviews authored by ‘volunteers’ rather than individuals who are either directly paid to do them or who (being health professionals and researchers) undertake reviews as part of their portfolio of professional work? The latter might arguably be conceptualised as different from individuals who have no professional considerations whatsoever in undertaking a Cochrane review.

Objectives: To categorise Cochrane authors in terms of the degree to which their participation is voluntary. To determine the proportion of a sample of Cochrane reviews that are the result of volunteer, professional or semi-professional effort.

Methods: All new reviews published in the Cochrane Library for 1 month (Issue 9, 2011) were retrieved and information extracted about the authors, including their review group, affiliations and sources of support. The lead author of each review was contacted for further information on each author’s primary reason for working on the review, selecting from four categories: as part of their paid job; as part of a course or training; as part of career development/for academic credit; voluntarily for none of these reasons.

Results: Thirty-five new reviews were published in the Cochrane Library in Issue 9, 2011. They were produced by 131 authors across 21 review groups. Information about the authors given in the reviews shows that all were affiliated to hospitals or universities. The survey of authors will be complete and information on the proportion of authors in each of the categories will be available before the Colloquium.

Conclusions: The amount of volunteer effort directly involved in preparing Cochrane reviews may not be as great as anticipated.