The current set of three proposed experiments focused on integrating neurological and behavioral levels of analysis in the context of pathological gambling. A thoroughgoing analysis on previous gambling research was explored and discussed in the first four chapters. Specifically, this analysis outlines: similarities between pathological gambling and other substance addictions, new technological advances (i.e. functional magnetic resonance imaging), verbal behavior in general and its role in pathological gambling specifically, and treatment assessments and interventions. Three experiments were then developed and designed based on the outcomes suggested by the literature review. Experiment I determined the effectiveness of the Gambling Functional Assessment (GFA; Dixon & Johnson, 2007) as a clinically relevant gambling assessment tool. Experiment II also investigated neurological differences between pathological gamblers. Similar to other behavioral and substance addictions, limbic and cortical brain systems are activated during gambling related tasks and activities. However, as gambling pathology increases, brain activation in these regions have been reported to decrease, and it is unclear how pathological gamblers brain activation patterns differ across function maintaining gambling (i.e. attention, escape, sensory, and tangible maintaining functions). Therefore, Experiment II built upon the findings of Experiment I by contrasting brain activation images from the two highest maintaining functions of play, as indicated by the GFA. Concomitantly, Experiment III assessed function based assessment and treatment of pathological gamblers, by comparing brief 30 min exposure to function based or non- function based Acceptance and Commitment Therapy for gamblers. Results from both studies suggested differences in brain activation patterns, yet similarities across subjective closeness to win ratings of the slot machine. Furthermore, brain activation patterns did not change following function based therapy, while subjective ratings in the function based treatment group decreased. Implications for brain-behavior relationships both in a gambling context and in relation to behavior therapy will be discussed.