For the past 20 years, I have conducted research with various participant groups, including children and young people and people with learning difficulties and mental health problems. There are a number of challenges of working with these groups of research participants, often defined as ‘vulnerable’. One challenge, which has been contentious in academic discourses and research practice, is the issue, and definition, of vulnerability. Another challenge is identifying and adopting research methods that are appropriate and effective for research participants who are vulnerable in some way. This case study explores these issues drawing on my own research. I focus on two participatory visual projects I have been involved with that involve young carers and people with learning difficulties. When working with vulnerable or marginalised research participants, it is important that the chosen methods allow for their ‘voices’ and perspectives to be heard and are beneficial to them personally and/or within community settings so that personal, social or political transformations can be realised. In my experience, participatory research methods are essential in facilitating such transformations, as well as in enhancing and advancing the nature and effectiveness of relationships, and understanding, between researcher and research participant.