Inhibitory or suppressive processes of the human brain are vital to daily function and goal-oriented behavior. This vital function becomes more acute in cases in which memories and thoughts are affectively negative based on traumatic experiences. In such cases, the uncontrolled memories and thoughts may disrupt on-going goal-directed behavior, and may characterize clinical conditions that apparently lack adequate inhibitory processes across an array of behavioral domains, such as PTSD, obsessive-compulsive disorder, ruminative anxiety and depression, and ADHD. A broad literature has examined suppressive brain processes in the motor realm, thereby establishing a base of knowledge about such processes in the brain. Less well studied, but equally important, are the suppressive processes underlying human cognition. Within the domain of memory, suppression research has mainly focused on the brain and behavioral mechanisms of automatic processes of forgetting; with much less attention having been directed to volitional, self-directed suppression of memory and thought (controlled MS). While automatic processes of forgetting are incontrovertibly important to human memory and cognitive functioning, they lie relatively outside of awareness and likely do not employ the same mechanisms as those used in the cognitive control processes involved in controlled MS. Accordingly, the current integrative dissertation addresses this deficit in our understanding of inhibitory processes in human cognition. The discussion thus focuses on controlled MS in order to critically examine the paradigms used to study this phenomenon, to discern the neuroanatomical circuitry supporting such processes, and to possibly shed light on the nature of clinical disorders that suffer from different forms of what appears to be weak inhibition of thought and memory.