Although often used as synonyms, "self-injury" and "self-harm" may refer to different behaviors with different meanings. Because the literature is quite confusing in this respect, we propose a more specific delineation of the notion of self-injurious behavior (SIB), differentiated from other self-harming behaviors. For this purpose, we present a flowchart for differential diagnosis. This brings us to the question: are we dealing here with a sign of pathology or a meaningful behavior? We compare the structuralist approach, in which SIB is viewed as either a syndrome or a symptom, with the functionalist approach, focusing on the psychosocial functions of SIB.