Gambling-related illegal behaviours are defined as illegal behaviours that occur after a person meets the criteria for gambling disorder (GD). The researchers examined how adults with GD might engage in illegal behaviours, and how this might be related to symptom severity and psychosocial impairment. The researchers used data from 427 adults with GD who participated in clinical trials. Participants were divided into two groups: those who engaged in gambling-related illegal behaviours and those who did not. About 43% of people with GD engaged in gambling-related illegal behaviours. This group was younger, started gambling earlier, and was younger when gambling first became problematic. Compared to people without legal problems, those with legal problems had worse gambling symptoms according to the Clinical Global Impression. They also reported more depressive symptoms, lower quality of life, and higher levels of nonplanning impulsivity.