Adjustment disorder is among the most frequently diagnosed mental disorders in clinical practice although it has received little academic attention and been the subject of substantial criticism over the past decades. While those suffering with adjustment disorders are often treated by mental health professionals, research interest in the origin of the disorder or the effectiveness of psychotherapeutic and medical interventions has only recently begun to emerge. This article summarizes the empirical literature published on adjustment disorder and points out current diagnostic developments in DSM-5 and ICD-11.