This question has plagued behavioral psychologists for a long time. Is substance abuse simply the result of peer pressure or is it a maladapted response to stress? Both of these may be valid reasons, but are they the only ones? Perhaps some people get started because they like the feel­ ing produced even if they are not under excessive stress. Often the beginning of drug abuse is seeking the apparent pleasurable effects such as euphoria, stimulation, sedation, or hallucinations. This stage is commonly followed by physical dependence produced by prolonged use of the chemical substance whose pharmacological action causes the body to adapt to its presence (tolerance). However, the most com­ mon beginning is usually due to peer pressure or as a response to real or imagined stress. Let us first look at some of the reasons and then focus on peer pressure and response to stress.