One of the greatest potential impacts of the sequencing of the human genome is individualized drug therapy. Currently, drug treatment is generally a trial and error process, with standard drugs and doses given to most patients. However, we each have a unique genetic profile, and it has been shown that genetic variation can significantly influence an individual's response to certain drugs. In the future, it may be possible to tailor drug therapy to an individual's genetic make-up, thereby avoiding ineffective medications and debilitating side effects. This book describes an attempt to uncover genetic variation that is predictive of response to two different antidepressants. It includes the interrogation of pharmacodynamic and pharmacokinetic candidate genes as well as an unbiased search of the entire genome. This work gives insight into the process of performing a clinical pharmacogenetic study as well as human genetic association studies in general. This book would be especially useful to academic and pharmaceutical researchers interested in pharmacogenetics, as well as psychiatrists, clinicians or patients interested in exploring the role of genetics in drug treatment.