This chapter explores how economic principles can be incorporated into a behavior-analytic approach using the Operant Demand Framework, a methodology for evaluating reinforcer effects across varying contexts. This chapter contrasts molecular and molar accounts of reinforcement and highlights how demand theory can offer a context-sensitive approach for understanding how reinforcers affect behavior in context. The work reviews foundational and contemporary research, with applications in substance use, safety practices, and interventions for individuals with developmental disabilities. Key concepts such as demand intensity, elasticity, and essential value are introduced alongside methods for evaluating reinforcer efficacy using Alone-Price and Cross-Price tasks. The chapter also discusses analytical strategies ranging from empirical visual inspection to advanced statistical modeling, emphasizing the importance of context, reinforcer markets, and schedule arrangements. Extensions to token economies, preference assessments, and schedule thinning are presented, illustrating how behavioral economics can enhance existing clinical and educational research and practice. Future directions include refining assessment tools, expanding applications across populations, and leveraging economic models to inform policy and intervention design.