In this chapter, which is focused on suboptimal choice and the associated clinical conditions that engender it, we devote particular attention to choices that are recurring and persistently suboptimal, that lead to the consumption of some commodity or event that provides an immediate and overvalued gratification, and that result in high costs over the long term. This problem of suboptimal choice is what we refer to as reinforcement pathologies. For our purposes, we define reinforcement pathologies as representing the combined effect of (a) the persistently high reinforcing value of a commodity or substance, broadly defined to include experiences and tangible consumables, and (b) the preference for the immediate acquisition or consumption of that commodity despite long-term negative outcomes. Prototypic examples of reinforcement pathologies include pathological overconsumption of various classes of psychoactive drugs and pathological overconsumption of food. To investigate this problem, we used an effective and increasingly used approach referred to as behavioral economics and the more recent approach of neuroeconomics. Behavioral economics as used here refers to the application of concepts and approaches from psychology and economics to the study of individuals ’ suboptimal choice behavior with respect to the costs and benefits of decisions. Neuroeconomics combines psychology, economics, and neuroscience to examine the neural correlates of decision making. We note that unlike traditional economics, neither behavioral economics nor neuroeconomics assumes that all choices are rational and optimal. Application of behavioral economics to addiction began during the 1990s as its concepts and measures were used in the analysis of drug-taking behavior with considerable success. During the late 1990s, the focus moved toward comparing the decision-making patterns of people with addiction and control participants, with a greater emphasis on the trade-offs between immediate and delayed outcomes. At the beginning of this century, the field of neuroeconomics began to study the neural correlates of those decision-making processes. The upshot of the field’s 2-decade movement has been the recognition, consistent with the aims of this book, that underlying processes are evident in many expressions of addiction. These underlying processes are consistent with the notion of syndromes as articulated by Shaffer et al. (2004), and we have termed them transdisease processes (Bickel & Mueller, 2009). Here we identify several of these processes that undergird our concept of reinforcer pathologies. In explicating the concept of reinforcement pathologies throughout this chapter, we address and review (a) basic knowledge about the processes underlying and determining choice, illustrated when possible with examples of suboptimal choice; (b) characteristics of reinforcement pathologies; (c) processes contributing to, and interacting to produce, choice of unhealthy reinforcers; and (d) processes contributing to, and interacting to produce, choice of healthy reinforcers. (PsycInfo Database Record (c) 2025 APA, all rights reserved)