Investigate alcohol and other substance use, with a focus on harmful alcohol use patterns, among young people in the Solomon Islands.A structured, interviewer-administered questionnaire was administered to respondents aged 15-24 years across four of the country's provinces in late 2015.Four hundred young people completed the questionnaire across urban, peri-urban and rural communities. The most common substances ever used by participants were betel nut (94%), licit/store-bought and/or illicit alcohol (79%) and tobacco (76%). Lifetime and recent substance use was particularly common among male respondents; e.g. 89% of male participants reported ever using any alcohol versus 54% of females (p<0.001). Harmful alcohol use patterns were common.Our sample generally reported higher levels of substance use compared to previous research in the Solomon Islands, including in relation to the country's relatively recent (2012/13) Household Income and Expenditure Survey. Implications for public health: Our study made considerable advances in addressing key knowledge gaps regarding alcohol and other substance use among young people in the Solomon Islands. Evidence-based initiatives to address early initiation of alcohol and other substance use and the progression to more problematic use patterns among young people in the Solomon Islands need to be explored.