The evaluation process for bariatric surgery needs to be multidisciplinary with evaluation and optimization of physical and mental health, as well as identification of prior obstacles for successful weight loss. Pre-operative evaluations for medical conditions that increase the risk of peri-operative risk, as well as an evaluation for conditions that may worsen post-operatively, are essential elements of the work-up. A psychologic assessment is an integral part of the evaluation of the patient seeking bariatric surgery, yet no consensus exists regarding necessary components of the evaluation. It is evident that patients seeking bariatric surgery have lifestyles incompatible with successful management of their weight. Tracking non-compliance with pre-operative recommendations often helps identify patients who are unmotivated and who may have poor compliance with dietary, physical activity, and vitamin/mineral supplements post-operatively. Bariatric surgery is an important tool for the management of the patient with medically complicated obesity.