Metacognition has been defined as cognition about cognition. Metacognition can include beliefs and attitudes about cognitive events such as thoughts, feelings, memories, images, sensations, and perceptions. Cognitive models of addictions have addressed the role of beliefs and attitudes in substance misuse, but the role of metacognition has been neglected. Metacognitive effects (beliefs about the effect of psychoactive substances on cognition) is differentiated from metacognitive consequences (beliefs about the effect of refraining from psychoactive substances on cognitive experience). In this study of 20 types of cognitive experience in 108 treatment-seeking substance abusers, the major metacognitive effects of drugs and alcohol were reduction, detachment from, and intensification of the cognitive event. The major metacognitive consequences of not consuming a substance included beliefs that the cognitive experience would be too uncomfortable, sleep would be disturbed, persistence of the cognitive event, and intensification of the cognitive event. An interaction between metacognitive effects and consequences and the type of cognitive event was found.