Even with the gradual upward trends in breastfeeding initiation and duration, breastfeeding rates at 6 months continue to lag well behind the 50% target set for any breastfeeding and the 25% target set for exclusive breastfeeding by the Healthy People 2010 initiatives. Overall evidence is limited in identifying effective interventions that promote breastfeeding duration and more research needs to be focused on specific nursing strategies and their effect on breastfeeding outcomes. The aim of this study was to test the efficacy of a daily feeding log, guided by Bandura’s social cognitive learning theory, on breastfeeding duration and exclusivity in primiparous mothers. The study used a randomized, controlled, two-group experimental design with a sample of 86 primiparous mothers. The experimental group completed a daily breastfeeding log for a minimum of 3 weeks and breastfeeding outcomes were examined over 6 months. The breastfeeding outcome variable was analyzed using survival analysis and Cox proportional hazards regression procedures. Subjects in the experimental group did not breastfeed significantly longer than the control group, however, a larger proportion of subjects in the experimental group reported full breastfeeding at 6 months as compared with subjects in the control group. Additional predictor variables were WIC enrollment, planned duration of breastfeeding, feeding frequency and feeding length at 1 week. The findings from the study suggest that the breastfeeding log may be a valuable tool in self-regulating breastfeeding and promoting a longer duration of full breastfeeding, but its acceptability may be impacted by socio-demographic variables.