The assumption that cannabis users are more likely to start using hard drugs, particularly heroin, is known as the stepping-stone hypothesis. Opinions about the accuracy of this hypothesis vary. It is clear that the switch from cannabis to hard drugs cannot be explained by the pharmacological characteristics of cannabis. No physical tendency to switch from lighter to heavier drugs has been found. However, social factors do appear to play a role: the risk of hard drug use increases as an individual becomes increasingly integrated into an environment (subculture) in which hard drugs are available as well as cannabis. It is therefore important to separate the drug markets, and this forms the basis of the Netherlands' current cannabis policy.

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