The purpose of this methodological investigation, part of a prospective cohort study, was to test the reliability and validity of the Breastfeeding Self-Efficacy Scale-Short Form (BSES-SF) among Aboriginal women.The sample comprised 130 breastfeeding Aboriginal women from the postpartum ward of an urban tertiary care hospital or a rural community hospital.The women provided baseline information while in hospital and were telephoned at 4 and 8 weeks postpartum for assessment of their method of infant feeding. The BSES-SF was found to be a valid and reliable tool for assessing breastfeeding self-efficacy among Aboriginal women. Significant differences were found in BSES-SF in-hospital scores among women who at 4 weeks postpartum were exclusively breastfeeding, combination feeding, or solely feeding formula (F(2) = 7.31, p = 0.001).The authors conclude that Aboriginal women with low breastfeeding self-efficacy in the early postpartum period may be at risk for early cessation and could benefit from additional breastfeeding support.