An Empirical Study of the Relationship Between Post-Traumatic Stress Disorder and Adolescent Substance Abuse seeks to address the co-morbidity of post traumatic stress disorder and chemical dependency. It utilizes surveys and statistical analyses of a relevant population located in Southern California. The study was designed using three complementary bodies of theory; these included (a) cognitive-behavioral psychology, (b) family systems theory and (c) developmental theory. The study was based on a causal comparative research design, with the objective of the statistical analysis being to explore the relationships between the independent and dependent variables.