Depression is the consistent and persistent low mood or sadness which negatively affects the normal activities and abilities to perform daily roles at work, school and/or community. it can be referred to as a feeling of despair or unworthiness, and/or hopelessness that one is unable to stop. Based on the world's most disease burden, depression is said to be the 2nd worst abnormality by the year 2020. It is further estimated that depression , being the world's most prevailing abnormality has 15% lifetime prevalence. Depression has very serious effects on the its victims; it affects their intellectual and physical abilities. Depression as an illness can be approached from several different perspectives attempting to explain its causes. This study seeks to explain the term depression in three different perspectives; Cognitive. Behaviorist and Humanistic, and critically examine this three models on how they are used to explain depression.