This chapter explores the relationship between anxiety symptoms, stress responding, and substance use disorders (alcohol and drug), with special emphasis on treatment approaches. Having an anxiety disorder increases the probability of having substance use disorder (SUD) with research showing the short-term effects of alcohol and drug use dampening stress responding. Factors that can contribute to individuals developing SUD include stress reduction alcohol and drug outcome expectancies, and avoidant and impulsive personality styles. Individuals with an SUD are at an increased risk for relapse following standard substance abuse treatment. This observation provides the basis for developing treatment approaches that specifically target SUD. Different treatment approaches for dual diagnosis are discussed, including parallel, sequential, and hybrid strategies. It concludes that hybrid treatment approaches that focus on the interactive aspects of stress, anxiety, and substance use are the most promising approaches for future study.