Data involving pregnant women is largely limited to case reports, case series and/or post-marketing surveillance (COPE Guidelines, 2011; https://www.womensmentalhealth.org">www.womensmentalhealth.org). For many psychoactive medications, determination of potential teratogenicity is made from small cohorts of several hundred women or less (Ray & Stowe, 2014; https://www.womensmentalhealth.org">www.womensmentalhealth.org). While the U.S. Food and Drug Association (FDA) assigns each medication a class based upon potential teratogenicity, these classes should be seen as a useful starting point during informed consent rather than an absolute determination of suitability in pregnancy (https://www.infantrisk.org">www.infantrisk.org). Providers should consider the risks versus benefits of each medication as well as consider a patient’s preference. This chapter is not a complete guide to care. Instead, this chapter should serve to assist providers in understanding the current evidenced-based research on various medications. Treatment should be specific to an individual patient; approaches may differ dependent on clinical context. Additionally, the field of medicine is perpetually changing; new evidence may be published in the future that contradicts evidence available upon writing this chapter. Clinicians are encouraged to use their best clinical judgment in the treatment of pregnant and postpartum patients. While there are many additional challenges to consider in the treatment of mental disorders in pregnant women as a whole, this chapter will focus on treatment in pregnant and postpartum women who are active duty or active duty family members. Treatment challenges and potential barriers to care may present differently in general pregnant and postpartum population and may have different challenges than treatment in a military setting.