Self-harm is a global public health challenge and the UK has one of the highest rates of self-harm across Europe. There is evidence to suggest that a large number of people are representing their self-harm online. Research on self-harm and the internet is an emerging field of inquiry which so far has focussed on whether social media use for self-harm is helpful or harmful. The aims of this research were to explore images tagged as self-harm on three social media platforms to identify what was being posted, to explore the meaning of images in relation to what they say about reasons for self-harm and motives for posting, and finally to understand how the social media platforms shaped the sharing of self-harm imagery. A total of 602 images were analysed from Twitter, Instagram and Tumblr. The images were analysed using a visual content analysis and a visual thematic analysis, which included a cross site analysis. There was also an exploration of the sites to understand their usability and how they supported, or hindered, the posting of self-harm imagery. Images posted onto these three sites were a mix of photography, drawings, collages and text. When self-harm was present the predominant method was cutting on the arms or legs. Females were also represented more than males. A number of themes were identified within and across sites which presented motivations for self-harm, ideas about the body, particularly the female body, motivations for posting images, and the link between self-harm and emotional distress. The findings from this research offer a new understanding of how people are utilising social media to share messages about self-harm. The results were considered in relation to broader self-harm literature, implications for clinical work and future research.