Background: The result of Basic Health Research (Riskesdas 2010) showed that the coverage of exclusive breastfeeding until 6 months were lower than the exclusive breastfeeding coverage target in Indonesia that is 80%. One of the factor that assumed can affect the continuity of exclusive breastfeeding is social economy condition. Methods: This study was a descriptive research with cross sectional design. Samples were taken from population who were mothers with 6-12 months old children within the area of Puskesmas Tanah Kali Kedinding on 2011. Closed quistionnaire was used to collect data and analyzed with Chi Square. The aim of the study was described the correlation between social economy factors and exclusive breastfeeding on babies. Result: Only a small portion of respondents that had good knowledge of exclusive breastfeeding. There was a significant correlation between good knowledge of exclusive breastfeeding with exclusive breastfeeding practice. There was a significant correlation between vocational status of mother and knowledge about exclusive breastfeeding with exclusive breastfeeding practice. There was no significant correlation between education level and family income with exclusive breastfeeding practice. Conclusions: The scope of exclusive breastfeeding must be enhanced. Poor of knowledge about exclusive breastfeeding and working mothers influence the low level of exclusive breastfeeding practice. Recomendation: Increasing knowledge of mothers and families about the benefits of exclusive breastfeeding, preparation and technical, as well as how storage and giving stored breastfeeding to the baby. Working mothers should try to give the exclusive breastfeeding which it must be facilitated by the company.