Smoking has well-known health hazards. It is associated with lung cancer, oral cancer, stroke, heart disease, emphysema, and other short- and long-term breathing problems. These troubling facts are very well-known to the public, both adults and adolescents. There is also a concerning association between the use of tobacco and other dangerous behaviours (eg: the use of other substances such as alcohol and marijuana and high risk sexual behaviour). Cognitive and mental problems including anxiety, depression and attention deficit/hyperactivity disorder are also associated with smoking. It is of great concern and frustration that all the above-mentioned facts do not prevent millions from starting to smoke every year around the world. In fact, smoking is practised by every nation on the planet and appears to take place in every society, regardless of race, colour or social status. In this book, we have gathered research from international collaborators to touch on these issues.