Background: To date, there are no studies examining the role of awareness of the World Health Organization's breastfeeding recommendation in determining mothers' breastfeeding decisions and practice. This study sought to determine whether awareness of the recommendation to breastfeed exclusively to age 6 months and intention to meet this recommendation are translated into breastfeeding practice. Methods: We analyzed longitudinal data from 201 first-time mothers who participated in the Healthy Beginnings Trial as a control group. The mothers' awareness of the breastfeeding recommendation and their intention to meet the recommendation were assessed at baseline antenatally, and breastfeeding duration was assessed at 6 and 12 months postpartum, through telephone and face-to-face interviews, respectively. Logistic regression and Cox regression analyses were conducted. Results: Mothers who knew the recommendation were 26% more likely to initiate breastfeeding (adjusted risk ratio [ARR] 1.26, 95% confidence interval [CI] 1.14 to 1.37, p=0.001) and 34% less likely to have stopped breastfeeding (adjusted hazard ratio 0.66, 95% CI 0.46 to 0.95, p=0.03) at 12 months than those who did not. Having an intention to meet the recommendation was weakly positively associated with the initiation of breastfeeding only (ARR 1.09, 95% CI 1.03 to 1.20, p=0.07). Conclusions: Awareness of the breastfeeding recommendation to breastfeed exclusively for 6 months is an independent positive predictor of breastfeeding initiation and duration. Improving mothers' awareness of the recommendation and strengthening their intention to breastfeed could lead to increased breastfeeding initiation and duration.