It may be easy to discount oral health in infancy because most infants are not born with teeth and only a few teeth erupt during the first year of life. Infancy, however, is a critical time for formation of habits. Positive habits, such as twice-daily brushing with fluoride toothpaste starting at first teeth eruption, provides topical fluoride, which is important for remineralization of the tooth and helps establish a lifelong healthy practice. Negative habits, such as bottle propping and frequent juice consumption, reinforce behaviors that promote caries and obesity. This article reviews normal dental development and eruption. Congenital anomalies affecting the mouth as well as acquired conditions, primarily dental caries, are reviewed. Oral health preventive modalities, including professionally applied products and home-based strategies, are discussed.