BACKGROUND: There is a need to increase our understanding of gambling behaviour, its antecedents, as well its influence on the health and wellbeing of gamblers and their families. OBJECTIVE: To determine whether the mental health and social/family correlates of gambling precede or follow gambling behaviour. METHOD: Analysing data from the Mater-University of Queensland Study of Pregnancy (MUSP), a prospective longitudinal study of maternal and child health. Commencing 1981-1983, health, behavioural and socio-demographic data were collected from mothers and children subsequent to maternal enrolment during the prenatal period. The most recent wave of data collection took place between 2002 and 2004 (Phase 7, the 21-year follow-up). OUTCOMES: Young adult's gambling behaviour is predicted by a individual factors, including being male, commencing smoking and alcohol use under the age of 15 years and having externalising behaviour problems in adolescence, and familial factors including maternal incomplete high school education, maternal tobacco and alcohol use in childhood or adolescence, problems in mother-child communication, and mother being in a de facto relationship during the child's developing years. Early predictors of high gambling expenditure include individual factors like commencing smoking, alcohol or cannabis use under 15 years and aggressive and delinquent behaviour measured at age 14; familial factors such as maternal anxiety, smoking, and alcohol consumption during childhood; and during adolescence changes in maternal marital status, problems in communication between mother and child, and maternal smoking and alcohol consumption. Parenting style appeared to be unrelated to young adult gambling. At 21 years, individual and environmental predictors were antisocial behaviour, endorsement of risk-taking beliefs and behaviours, and living in a neighbourhood with numerous social problems. Conversely, young adults who engaged in religious practices were found to spend less money on gambling activities. 11.3% of the sample reported one or more gambling-related problems (CPGI). Risk factors found to have an independent effect included: being male; the child's mother being in a de facto relationship at the time of adolescence; smoking up to 9 cigarettes per day in adolescence; and commencing smoking or 5 drinking prior to age 15 years. Young adults who had been exposed to 5 or more of these influences were found to be much more likely to have gambling problems. CONCLUSION: It is likely the personal characteristics which might lead a young person to smoke tobacco and drink alcohol, also have an impact on that person's gambling behaviour, either because they are less tied to some social norms, and because they have biological characteristics that predispose them towards risk-taking behaviours. However, while ecological, emotional and biological predictors are generally statistically significant predictors of gambling behaviour, they are weak. Intervening on the basis of risk is generally not an efficient or effective strategy. Primarily, policy initiatives may need to focus on exposure and opportunity variables. Perhaps what are needed are new types of responses which focus on early intervention for those experiencing the early stages of problem gambling.