Objective: To determine the relationship between exclusive breastfeeding with the level of Psychosocial development of preschool children (4-6years).Methods: The categorical analytic study with cross sectional approach. Samples were children aged 4-6 years who accompanied the mother and go to school in kindergarten of Merpati Pos, early childhood education Melati and Kartika in the year 2014 to 2015 were taken with stratified sampling technique and simple random sampling method. Data were obtained from interviews at the child's mother, and analyzed with Chi Square test.Results: The number of samples in this study were 84 cases. Most long breastfeeding is more than 6 months is 61 persons (72.6%) with a pattern of exclusive breastfeeding as many as 76 people (90.5%). Children with a long history of breastfeeding for more than 6 months tend to have normal psychosocial development of as many as 40 people (37.8%). And children with a history of exclusive breastfeeding patterns have normal psychosocial development than not exclusive as many as 47 people (61.8%).Conclusion: in this study, the results of a statistical test obtained value P>0,05. This means that there is no relationship between a history of exclusive breastfeeding (duration of administration and pattern / intensity of breastfeeding) with the psychosocial development of preschool children (4-6 years) in kindergarten of Merpati Pos, early childhood education Melati and Kartika in the year 2014 to 2015

Keyword: Exclusive breastfeeding history, Psychosocial Development.