This viewpoint article discusses the utility of high-dosage experiments (HDEs) in everyday life to test theories in clinical science. HDEs involve experimental manipulations and assessments that occur over much longer periods of time than traditional experiments-generally days or even weeks. By nature, they also occur outside the lab, in the everyday environments of participants. Additionally, as with other experiments, the purpose of the study is concealed from participants. Experimental design is one of the most distinguishable characteristics of psychology that separates it from other behavioral sciences. Studies that rely on experiments are essential for theory testing and establishing the potential causal role of mechanisms that underlie psychopathology. Yet despite the value of experimental research, experimental studies are not currently given special prominence in clinical psychological science. For example, in the Journal of Psychopathology and Clinical Science, of all the empirical studies in the most recent year (2023), only three of 77 incorporated an experimental manipulation. Experimental research appears to be less popular in clinical psychology than in other fields, such as social psychology. What might account for this discrepancy? First, clinical samples are more difficult to recruit. This is important because experimental manipulations may produce small effects that require large samples for detection. Additionally, mechanisms hypothesized to underlie psychopathology are often chronic and intransigent. For example, cognitive factors (e.g., perfectionistic beliefs) could require an especially strong manipulation to modify in isolation. Researchers have argued that psychology has been experiencing a crisis in theory development. Eronen and Bringmann (2021) stated that one major reason for this crisis is the difficulty in establishing causal relationships between psychological constructs. The replication crisis has garnered even more attention (Open Science Collaboration, 2015). HDEs would help address these two crises and provide stronger and more replicable tests of theory. This could allow us to more precisely identify important mechanisms underlying psychopathology, potentially enhancing treatment efficacy, and enabling us to move the field forward. (PsycInfo Database Record (c) 2024 APA, all rights reserved).