This study explores the longitudinal pathways by which risk and protective factors influence the development of alcohol-related harms in a representative community sample of 941 young adults (19-20 years) from Victoria, Australia, focusing on the role of concurrent risky drinking. Impulsivity at 15-16 years, alcohol-related harms at 15-16 years and 17-18 years, frequency of intoxication at 17-18 years, and antisocial behavior, friends' drinking and living arrangements at 19-20 years were directly related to alcohol-related harms, as well as indirectly related to harms through increased risky drinking. Paternal drinking at 17-18 years was directly related to alcohol-related harms. Friends' drinking at 19-20 years and alcohol-related harms at age 17-18 interacted with risky drinking to increase the likelihood of alcohol-related harms. Implications for intervention efforts are discussed.