In Chapter 5, we discussed the growing concept of precision medicine and its forerunner term, “personalized medicine,” as the initiative to craft individually tailored treatments. For psychiatry, precision medicine represents the goal of utilizing a given patient’s unique clinical and biological profile in order to broker the best fit with a particular drug regimen. That theme is woven throughout this book, as the means by which clinicians must interpret large-scale clinical trials and decide whether and how their findings apply to an individual case. In the minds of many psychopharmacologists, pharmacogenetics and pharmacogenomics represent a key component, if not the key component, of that endeavor, based on assumptions that everyone’s unique genetic architecture must figure critically in how they will respond to a drug – and that without such information, efforts toward devising an appropriate pharmacotherapy regimen are merely trial and error.