We assessed nonprofessionals’ perceptions of etiological explanations of behavioral and substance addictions in a nationwide sample. A total of 612 adults (51% male) residing in the United States were recruited using Mechanical Turk. Participants rated the perceived likelihood of seven psychosocial and biological etiologies for one of five randomly assigned types of “addiction” (i.e., alcohol, marijuana, heroin, gambling, or pornography). Significantly fewer participants rated social pressure a likely cause of addiction to pornography (31%) than to marijuana (53%), alcohol (55%), and heroin (64%); significantly fewer rated traumatic childhood events a likely cause of addiction to gambling (33%) and marijuana (36%) than to pornography (56%), heroin (57%), and alcohol (64%); significantly fewer rated the way a person was raised a likely cause of addiction to marijuana (37%) than to heroin (55%) and alcohol (65%); and significantly more rated genetics a likely cause of an addiction to alcohol (65%) than to pornography (26%), marijuana (33%), gambling (41%), and heroin (45%). The proportions who rated stressful circumstances and character problem a likely cause were not significantly associated with type of addiction. In addition, participants rated an average of three or four separate etiologies as likely causes of each target addiction. Our results suggest that lay individuals recognize the multi-determined nature of addictive disorders and rate some causes as more or less likely depending on the specific addictive substance or behavior.