Abstract: Background: Despite high levels of breastfeeding initiation in Australia, only 46 percent of women are still breastfeeding (exclusively or partially) 6 months later, with marked differences between social groups. This study aimed to determine the influence of mid‐pregnancy breastfeeding education on the proportions of women breastfeeding at hospital discharge, and on the duration of breastfeeding. Methods: A randomized controlled trial to compare two strategies for increasing the initiation and duration of breastfeeding was conducted, in which 981 primiparas who attended a public, tertiary women's hospital in Melbourne, Australia, were randomized to one of two interventions or to standard care (327 in each group). The interventions were a 1.5‐hour class on practical aspects of breastfeeding using a previously tested tool (Practical Skills), and two 1‐hour classes exploring family and community attitudes toward, and experiences of, breastfeeding (Attitudes). Both interventions took place in interactive small groups when women were in mid‐pregnancy. Breastfeeding initiation was ascertained by interview 2 to 4 days after birth, and breastfeeding duration was assessed by telephone interview 6 months after birth. Results: Neither intervention increased breastfeeding initiation or duration compared with standard care. Rates at initiation were 97 percent (296/306) for the Practical Skills intervention, 95 percent (291/308) for the Attitudes intervention, and 96 percent (297/310) for standard care. Rates at 6 months were, respectively, 55 percent (162/297), 50 percent (146/293), and 54 percent (162/299). Conclusions: In settings where breastfeeding initiation is already high, neither study intervention could be recommended as an effective strategy to increase breastfeeding initiation or duration.