No current breastfeeding assessment tool assesses the mother's perception of breastfeeding effectiveness during the early postpartum. Psychometric analysis of a new tool, the Beginning Breastfeeding Survey (BBS), in a multi-racial sample of 131 women revealed a coefficient alpha of .90. Factor analysis yielded three factors, (a) Maternal Breastfeeding Competence and Emotional Satisfaction, (b) Maternal Discomfort and Anxiety, and (c) Infant Breastfeeding Skill and Emotional Satisfaction. The BBS demonstrated discriminant validity in known group analyses and convergent validity with breastfeeding self-efficacy and postpartum fatigue. Future research will focus on improving the internal consistency reliability of the BBS and examining its ability to identify women at risk for breastfeeding problems during the postpartum hospitalization. © 2010 Wiley Periodicals, Inc. Res Nurs Health 33:329–344, 2010