Steppingstone theory

According to the steppingstone theory, people who use one substance such as nicotine will go on to drink alcoholic beverages, smoke marijuana, and progress on to use hard drugs such as cocaine. Each step is seen as leading to the next step in substance use. It suggests an inevitability of progressive use not necessary to the gateway theory, with which it is commonly confused.

Source

 * Gateway and Steppingstone Substances