Gambling is quite common among youths in Nigeria. Parental monitoring and herding bias may influence youth gambling. Parental monitoring refers to parents being aware of their children’s activities and whereabouts, including when they are with peers. Herding bias describes a tendency to follow others’ decisions without thinking about the outcomes. In this study, the researchers surveyed 238 male students between the ages of 16–19 years. All of the youths had bet on soccer in the previous two weeks. The results showed that herding bias influenced the relationship between parental monitoring and problem gambling. For youths with a low level of herding bias, higher parental monitoring was associated with less problematic gambling behaviours. However, for youths with a high level of herding bias, higher parental monitoring was associated with more problematic gambling behaviours.