Studies from the West suggest that significant numbers of high school students gamble, despite it being illegal in this age group. To date, there have been no studies on the prevalence of gambling among senior high school and higher secondary school students in India. This study reports point prevalence of gambling and its psychosocial correlates among high school students in the State of Kerala, India. 5043 high school students in the age group 15–19 years, from 73 schools, were selected by cluster random sampling from the district of Ernakulam, Kerala, South India. They completed questionnaires that assessed gambling, substance use, psychological distress, suicidality, and symptoms of Attention Deficit Hyperactivity Disorder (ADHD). Of a total of 4989 completed questionnaires, 1400 (27.9 %) high school students reported to have ever gambled and 353 (7.1 %) were problem gamblers. Of those who had ever gambled, 25.2 % were problem gamblers. Sports betting (betting on cricket and football) was the most popular form of gambling followed by the lottery. Problem gamblers when compared with non-problem gamblers and non-gamblers were significantly more likely to be male, have academic failures, have higher rates of lifetime alcohol and tobacco use, psychological distress, suicidality, history of sexual abuse and higher ADHD symptom scores. Gambling among adolescents in India deserves greater attention, as one in four students who ever gambled was a problem gambler and because of its association with a range of psychosocial variables.