This case study presents the case of Nancy, a 27-year-old married woman diagnosed with moderate single-episode major depressive disorder. The study details Nancy's history, including childhood instability, postpartum depression, and current symptoms such as insomnia, withdrawn behavior, suicidal ideation, and loss of interest. It outlines her medical and psychiatric history, including previous treatments with Paxil and Zoloft. The diagnosis is based on her presenting symptoms, ruling out other potential conditions. The treatment plan includes Citalopram, psychotherapy, and lifestyle changes such as dietary adjustments, exercise, and sleep hygiene. The study also highlights the use of cognitive behavioral therapy and the setting of treatment goals. The case underscores the importance of a comprehensive approach to managing depression, combining medication, therapy, and lifestyle modifications.