This study of homeless youth uses quantitative data to estimate the prevalence of high-risk smoking practices (obtaining or using cigarettes in a way that increase exposure to toxins and/or susceptibility to infectious diseases) and identify characteristics associated in particular with sniping (smoking discarded cigarettes), and qualitative data to describe why and how homeless youth engage in sniping.A probability sample of 292 homeless youth smokers in Los Angeles County completed a self-administered survey, and a separate convenience sample of 27 homeless youth who were lifetime smokers participated in focus groups. Survey participants reported on background characteristics, smoking cognitions, and high-risk smoking practices. Focus group participants described how they obtained cigarettes and responses relevant to sniping were coded.Survey results indicated that nearly all youth engaged in at least one high-risk smoking practice, with three-quarters having sniped cigarettes in the past 30 days. Sniping was more frequent among youth with less negative smoking attitudes (b=-0.29, 95% CI=-0.55 to -0.04, p=0.02), greater nicotine dependence (b=0.11, 95% CI=0.00 to 0.23, p=0.046), lower income (b=-0.05, 95% CI=-0.09 to -0.01, p=0.02), and more severe drug abuse (b=0.15, 95% CI=0.04, 0.26, p=0.01). Focus groups data indicated that youth snipe because it provides cheap and easy access to tobacco, and use specific strategies to mitigate the perceived health risks of sniping.Sniping and other high-risk smoking practices deserve further attention among homeless youth, particularly those already facing greater health threats due to factors such as nicotine dependence, lower income, and drug abuse.