This study provides the first analysis ever made of a representative national sample of Internet gamblers. Using participant data from the 2007 British Gambling Prevalence Survey (n = 9,003 adults aged 16 years and over), all participants who had gambled online, bet online, and/or used a betting exchange in the last 12 months (n = 476) were compared with all other gamblers who had not gambled via the Internet. Overall, results showed a number of significant sociodemographic differences between Internet gamblers and non-Internet gamblers. When compared to non-Internet gamblers, Internet gamblers were more likely to be male, relatively young adults, single, well educated, and in professional/managerial employment. Further analysis of DSM-IV scores showed that the problem gambling prevalence rate was significantly higher among Internet gamblers than among non-Internet gamblers. Results suggest that the medium of the Internet may be more likely to contribute to problem gambling than gambling in offline environments.