This study examines the cognitive and social psychological factors underlying UK National Lottery play. A total of 384 respondents were asked about their own lottery playing behaviours, their knowledge of lottery odds and their beliefs about the role of skill, chance, luck and optimism in lottery play. Using hypothetical scenarios, respondents were also asked to rate the likelihood of winning the lottery jackpot (matching all six numbers) with number combinations reflecting different levels of apparent randomness, previous matches, near misses and prize size manipulations. Frequency of lottery play was found to be positively correlated with age, income, Instants scratchcard play, gambling on horse/greyhound racing, the football pools, and bingo as well as with beliefs about skill, luck and optimism. Frequency of lottery play was negatively correlated with general education and estimate of relative win likelihoods based on the perceived randomness of number combinations. Planned contrasts revealed that compared to individual (non-syndicate) players, syndicate lottery players played more regularly and gambled more on the football pools. Results are discussed in the light of current cognitive theories surrounding the misperception of probability and their relation to lottery play and in the need for future models to recognise the social factors inherent in syndicate-based lottery participation.