This study uses the theory of planned behavior (TPB) to explain why some people play the lottery, and it examines how the TPB's variables and variable relationships differ due to ethnicity, or gender, or their interaction. A telephone interview conducted in English, Cantonese, and Mandarin resulted in data on the lottery play intentions of 208 Chinese/Canadians (97 males, 111 females) and 220 British/Canadians (112 males, 108 females). When intention to play the lottery was regressed on six TPB variables, it was found that: (a) affective attitude was an important predictor for all four groups, while instrumental attitude was only important for British/Canadian males; (b) injunctive norm was an important predictor only for Chinese/Canadian males, while descriptive norm was an important predictor only for British/Canadian males; (c) controllability was an important predictor only for Chinese/Canadian females, with a negative coefficient suggesting secondary control; and (d) self-efficacy was not an important predictor for any of the groups. A follow-up mail questionnaire provided additional data on the self-reported lottery play behavior of 100 Chinese/Canadians (51 males, 49 females) and 115 British/Canadians (57 males, 58 females) 30 days after the initial telephone interview was conducted. When lottery play behavior was regressed on self-efficacy, controllability, and intention, intention was found to be an important predictor for all four groups. These findings are discussed in light of recent research on the TPB, leisure and gambling, and ethnicity and gender.