Secondhand smoke or environmental tobacco smoke is a combination of smoke from a burning cigarette and exhaled smoke from a smoker. This substance is an involuntarily inhaled mix of compounds that causes or contributes to a wide range of adverse health effects, including cancer, cardiovascular diseases, respiratory infections, adverse reproductive effects, and asthma. This paper presents findings from Global Youth Tobacco Surveys (GYTS) conducted in 132 countries between 1999 and 2005. GYTS data indicate that a large proportion of students in every World Health Organization Region are exposed to secondhand smoke at home (43.9%) and in public places (55.8%), and many have parents (46.5%) or best friends who smoke (17.9%). GYTS data have shown widespread and strong support among students for bans on smoking in public areas all over the world (76.1%). Countries should engage this positive public health attitude among youth to promote and enforce policies for smoke-free public places and workplaces, including restaurants and bars.