Scope of the Problem and the Nature of Drug Use Consequences -- Theories of Drug Use Consequences -- Study Sample and Design -- Constructs and Measures -- Methodological Considerations and Analytic Approach -- The Reciprocal Influence of Drug Use on Social Conformity An Example of Our Analytic Approach -- Impact on Family Formation and Stability -- Impact on Criminality and Deviant Behavior -- Impact on Sexual Behavior and Involvement -- Impact on Educational Pursuits -- Impact on Livelihood Pursuits -- Impact on Mental Health -- Impact on Social Integration -- Impact of Specific Drugs in a Large Integrated Model -- Integration and Conclusions.