Background: Self-harm (SH) accounts for over 5% of the workload of emergency ambulance services, and therefore Paramedics are often the first health professional in contact with people who SH. The authors of this paper have reported elsewhere the significant gaps in our understandings which exist surrounding this early care interaction, and some of the challenges paramedics and opportunities in paramedic care for people who SH. This study aimed to explore paramedics' perceptions of caring for those who SH using Evolved Grounded Theory Methodology. Methods: This study took place between 2014-2016 in one UK ambulance service covering a population of three million people. Semi structured interviews were conducted, purposively sampling paramedics until saturation was reached. Interviews were recorded, transcribed verbatim, and coded through open, axial, and selective levels of coding, identifying the Basic Social Process (BSP) and developing a Grounded Theory. A second researcher (SH) independently reviewed early results, which were also member-checked with participants. Results: Eleven paramedics were interviewed. The following six categories emerged: Context; Judgements and values; Isolation and system failure; Managing risk; Competence at the boundary of mental and physical health needs; Professional, legal and ethical tensions. The BSP Decision making in a context of risk was identified. The final Grounded Theory that emerged was one of 'Wicked Complexity of paramedic care for people who SH, which includes usual factors such as tiredness and frequent callers, heightened factors including lack of support and pathways, and factors specific to SH such assessing mental health and suicide risk. Conclusions: This study builds on a very small body of literature to have explored paramedic care for people who SH and has found that this care interaction provides uniquely complex challenges. The multiple influences within the categories defined in this study need considering conjointly when making improvements to care.