Mood disorders refer to a group of elevated and depressed mood conditions. These are classified as depressive disorders, bipolar disorders, substance-induced disorders or triggered by other medical conditions. Major depressive disorder or depression is a disorder that is characterized by low mood present across all situations and accompanied by a loss of interest in normally enjoyable activities, low self-esteem, low energy and pain caused by an unidentifiable cause. Antidepressants are generally recommended for people with depression. Bipolar disorder is another mental disorder, which causes periods of abnormally elevated mood and depression. During the elevated phase, an individual feels abnormally energetic, happy or irritable, while during depressive periods, there may be a general negative outlook towards life, crying and poor eye contact with people. Antipsychotics, mood stabilizers and melatonin may be prescribed for the treatment of bipolar disorders. This book is a compilation of chapters that discuss the most vital concepts and emerging trends in the diagnosis and treatment of mood disorders. It aims to give a general view of the different types of mood disorders and their implications in the psychological health of individuals. Students, researchers, experts and all associated with psychiatry, psychology and neurology will benefit alike from this book.