Background: Volunteers and citizen scientists have become an essential element of most nature conservation and restoration activities due to lack of resources but also due to the wish to engage and interact with local communities where conservation activities take place. Environmental or conservation volunteering is also considered to be a key resource in achieving much needed, ambitious nature restoration programs. Practical conservation work and various forms of environmental enhancement along with recreational and therapeutic use of natural or green and blue spaces have been studied for some time. The value of volunteers and the work is widely acknowledged but few studies have been carried out on the impacts of participating on the volunteers themselves. Using this protocol, a study will be undertaken to assess how impacts of participation have been assessed and reported in the literature; what these reported impacts are; how these are related to reported barriers and motivations for volunteering and whether they are affected by the region or country of study. Methods: This paper will identify studies that have described and assessed impacts of conservation and restoration volunteering on participants at an individual level, with a specific focus on physical, mental or societal wellbeing of individuals. Representative studies were sought from major search engines and relevant stakeholder publications, including both peer-reviewed and ‘grey literature’ in predominantly English language publications, published between 2000 and 2020. A priori inclusion criteria consisted of those publications and reports on studies with volunteer and community participants and which described impacts of, motivations for and barriers to participation. After a critical appraisal, a total of 105 articles were selected for further analysis to provide a narrative and mixed methods synthesis of the evidence base.