Despite five decades of research into the harms of smoking and numerous successful public health campaigns, many people take up and continue with the habit. Cigarette sales remain high as tobacco companies excel at marketing. In the United States, more than $8 billion was spent by the tobacco companies on marketing and advertising in 2011-12, compared to $457 million spent by the government in preventing or reducing tobacco use. This lecture will explore what has been learnt from 50 years of research, including the benefits of quitting at any age, and plans for future policies.