An increasing number of research studies over the last three decades suggest that a wide range of substance and process addictions may serve similar functions. The current article considers 11 such potential addictions (tobacco, alcohol, illicit drugs, eating, gambling, Internet, love, sex, exercise, work, and shopping), their prevalence, and co-occurrence, based on a systematic review of the literature. Data from 83 studies (each study n = at least 500 subjects) were presented and supplemented with small-scale data. Depending on which assumptions are made, overall 12-month prevalence of an addiction among U.S. adults varies from 15% to 61%. The authors assert that it is most plausible that 47% of the U.S. adult population suffers from maladaptive signs of an addictive disorder over a 12-month period and that it may be useful to think of addictions as due to problems of lifestyle as well as to person-level factors.