Mental health conditions are very common. In 2015, it was estimated that over 300 million people world-wide have depression and, in Canada, more than 1-in-10 people will suffer a major form of depression at some point in their lives. There are many effective treatments for mental health conditions, including talk-based therapies and drugs. Currently in British Columbia, it is common for drug therapy to be used. The choices of drugs include a range of antidepressants. For people with mental health conditions, finding a medication that both works and does not cause severe side-effects is often a matter of trial-and error. An individual’s genetic makeup is thought to be part of the story in terms of whether particular drugs work and whether there are side-effects with the drug. “Pharmacogenomics” testing (that is, seeing if the patient’s genetic makeup is suitable for the particular drug) is a new and promising approach. In this study, we want to know if such testing should routinely be used in B.C. We want to know how much improved health patients might see, as well as whether the testing is good value for money for the health system. To do this work, we have created a team that includes people with very different backgrounds and skills who are interested in working together. An exciting part of the project is that we will have at least two patients with mental health conditions as part of our team, working with us on all parts of the project. Our work will involve reviewing the research others have already done, so we can learn from existing studies. We will also talk to patients, doctors, nurses, pharmacists, counsellors, and others providing care for patients with mental health conditions in B.C. We will collect information from the records kept by the health care system. Together, all of this information will allow us to describe the typical experiences of patients and, using something called a “simulation model,” we will be able to count the health benefits to patients and the costs to the system of changing practice to include routine use of “pharmacogenomics” testing. If we find that pharmacogenomics testing is good for patients and the health system, this information might change care for depression in B.C. The main benefit would be from prescribing drugs to patients only when there is a high chance of them working and not giving side-effects.