Self-regulation, the ability to guide behavior according to one’s goals, plays an integral role in understanding loss of control behaviors a pertinent example being substance use disorders (SUD). Yet, experimental tasks that measure processes underlying self-regulation are not easy to deploy in contexts where such behaviors often occur, namely in real life situations outside the laboratory. Moreover, lab-based experimental tasks are criticized for poor test–retest reliability and a lack of construct validity. These concerns might in part explain why ecological validity of experimental measures—their ability to predict real-life behavior—is low. To address these shortcomings, we assessed the reliability and construct validity of four smartphone-based experimental tasks designed to measure cognitive control and decision-making. To facilitate future clinical applicability we recruited a large (N=488) sample of individuals with SUD. Joint modeling of measurement sessions increased the reliability of task measures from moderate to good and often excellent levels. In line with theories of cognitive control and motivation, three latent factors reflecting cognitive control and decision-making in the context of gains and losses best described the data. As proof of concept, we show that a latent cognitive control score based on joint modeling, yielded stronger correlations with drinking behavior than single task scores based on separate modeling. These findings indicate that in individuals with SUD, smartphone-based ambulatory experimental assessments can reliably index functions of cognitive control and decision-making, with plausible construct validity. Our findings provide evidence for rich possibilities arising from longitudinal experimental studies in SUD as well as in psychiatry, neuroscience, and psychology more generally.