Exclusive breastfeeding to 6 months with continued breastfeeding up to 2 years and beyond are well-established infant feeding recommendations based on evidence that breastfeeding has unparalleled maternal and infant health benefits as well as environmental and economic benefits. As with many high-income countries, breastfeeding rates remain suboptimal with only a quarter of Canadian and European infants receiving breast milk exclusively for the first 6 months. Breastfeeding promotion efforts have largely targeted caregivers in the prenatal and postnatal period; however, breastfeeding outcomes have been shown to be associated with broader sociocultural factors. Noncaregivers play an influential role in infant feeding at both an individual level (e.g., cues and input from health care practitioners and caregivers' social networks; as future parents) as well as a broader population level (sociocultural norms and policy decisions). This paper outlines recent research on breastfeeding knowledge and attitudes of noncaregivers by population subgroup. Positive correlations have been identified between breastfeeding attitudes, infant feeding knowledge, breastfeeding exposure, and breastfeeding intention among different subgroups; however, key knowledge gaps, lack of exposure to breastfeeding, and negative public perceptions of breastfeeding persist. Dietitians can advocate for breastfeeding promotion strategies that consider the role of noncaregivers to address sociocultural norms around breastfeeding.