The Substance Abuse and Mental Health Services Administration (SAMHSA) and the Center for Substance Abuse Prevention (CSAP) define prevention as a proactive process that empowers individuals and systems to meet the challenges of life events and transitions by creating and reinforcing conditions that prompte healthy behaviors and lifestyles.

According to SAMHSA, the goal of substance abuse prevention is the fostering of a climate in which:

• Alcohol use is acceptable only for those of legal age and only when the risk of adverse consequences is minimal
• Prescription and over-the-counter drugs are used only for the purposes for which they were intended
• Other abusable substances (e.g., aerosols) are used only for their intended purposes
• Illegal drugs and tobacco are not used at all

The Institute of Medicine (IOM) uses a model of prevention that describes three concepts for targeting individuals or groups with interventions.  The three categories are:

• Universal - prevention measures that address an entire population with messages and programs aimed at preventing or delaying the use of alcohol, tobacco and other drugs.  The goal of universal prevention is to provide all individuals with information and skills necessary to prevent the problem.  The entire population is considered to be at risk and able to benefit from universal prevention programs.
• Selective - selective prevention measures target subsets of the entire population that are considered at risk for substance abuse.  Examples might include children of alcoholics, students failing academically or children living in high drug use neighborhoods.  Selective prevention targets the entire subgroup. 
• Indicated - indicated prevention measures are designed to prevent the onset of substance abuse in individuals who are showing early danger signs, but do not meet the medical criteria for addiction.  Danger signs may include use of alcohol or marijuana, or falling grades.  The goal of indicated prevention is to identify individuals exhibiting early signs of substance abuse and other problem behaviors and to involve them in special programs.