The intention of this master thesis is to examine Non-Suicidal Self-Injury (NSSI) in the light of Addiction of Psychoactive Drugs (APS) from a general psychological perspective, and how the general definition of normality and sickness is influenced by the diagnostic classification sycstems and the current society. NSSI is a phenonomen where a person inflicts harm on themself with no intention of suicide. At the moment NSSI is not an independent diagnosis but only a symptom of other psychiatric illnesses and presented in the Diagnostic Statistical Manual-5 as a diagnosis for further research. Studies have shown that NSSI and APS have similar aspects, where addiction can be seen as a type of indirect self harm. We seek to investigate whether we can view and expand our understanding of NSSI by looking at the possible addiction aspects of self injurious behavior. This is done through an eclectic and social constructivist approach and by using the critical interpretative synthesis (CIS) model to select relevant litterature. We present the empirical background for our thesis through the bio-psycho-social model, where we focus on understanding the phenomena through risk and maintenance factors as well as treatment options for both. This creates the base for a comparison, where we find that several factors are the same and that there is a complex interaction between the biological, psychological and social factors in both phenomena. We find that they share a neurological effect, where the amygdala and endogenous opioids play an important role in both. There are also elements of positive and negative reinforcement, where the harmful behaviors can become effective yet maladaptive copingstrategies, and anxiety disorders and depression often occur simultaneously with NSSI and APS. They also share specific personality traits such as sensation or novelty seeking, impulsivity and reduced ability to evaluate consequences of actions. Unstable family relations, negative relations to peers and the need to be part of a group are also important for understanding NSSI and APS. We find that auto-addiction can occur in persons who engage in NSSI, where the body will become addicted to its own natural substances, which leads to addiction-like symptoms such as cravings, abstinences and increase in tolerance. We use this knowledge to find ways in which we can specify the criteria for NSSI-D by including these addiction aspects and by using the diagnosis for substance addiction as an inspiration. This also leads to an increase in the focus on identifying specific subgroups of patients engaging in NSSI with the purpose of bettering assessment and treatment options. In our thesis we understand these phenomena in the context of how the definition of normality and illness can push the individual to a breaking point in a society that already is heavily focusing on performance and self-realization. Both the society and the individual is seeking explanations of deviations through the diagnostic classification systems and craving diagnoses to be able to gain access to treatment and support from the healthcare system. In this chase for diagnoses and creating the best version of yourself we end up in a society where NSSI and APS becomes signs of inadequacy that in reality are symptoms of a narrowed definition of normality, which makes it difficult to remain and be seen as healthy. Lastly in our thesis we reflect on our profession as upcoming psychologists and our methodological approach.