Non-suicidal self-injury (NSSI) is defined as the direct and deliberate destruction of one’s own body tissue in the absence of lethal intent. Following decades of progressive increase in the incidence of NSSI among adolescents and young adults, as well as growing scientific interest, the disorder was listed as a condition for further study in the Diagnostic and Statistical Manual of Mental Disorders (fifth edition). In this review we provide updated information on this phenomenon, focusing on: prevalence, course and prognosis; associated factors; its relationship with psychopathology; and the role of the mass media, social networks, and the internet. Finally, we discuss some conclusions and future proposals, emphasizing the need for collaborative work to better understand NSSI in Spain, and to improve prevention and treatment strategies.