The concept of addiction, traditionally applied to psychotropic substances, has been officially extended by the DSM-5 to gambling disorder, a “behavioural addiction” (BA), in which the focus of the addiction is represented by a specific behaviour. BAs are emerging psychopathological disorders with an increased in scientific interest and socio-cultural and economic implications. In this paper, we will review the available evidence on the clinical, diagnostic and psychopathological features of BAs, with particular reference to gambling disorder, sex-addiction, compulsive buying, exercise, work, technological and love addictions. Even though each of these addictions may likely meet the requirements for classification as a separate diagnostic entity, at present, the only two disorders included in DSM-5 are gambling disorder and internet gaming disorder. The absence of specific diagnostic criteria, the present of difficulties in differentiating pathological from “normal” behaviours, and blurring of demarcation lines between physiology and pathology complicate the epidemiologic investigation and diagnostic assessment of BAs. Moreover, the lack of valid screening tools and the frequent comorbidity with other mental disorders further hinder the diagnostic approach to BAs. Therefore, clear-cut and well-defined diagnostic classification needs to be established, along with a better understanding of the clinical and psychopathological features of BAs, as a fundamental prerequisite to prevention, early diagnosis and treatment.