Cow's milk and dairy products intake increase linear growth in children and result in increased adult stature. This is supported by observational and intervention studies mainly from low- and middle-income countries. However, recent reviews primarily based on studies from well-nourished populations question the relation. The probable effects seem to be mediated by insulin-like growth factor-1 and insulin and to be more pronounced during periods of high growth velocity. Several components of cow's milk are suggested to stimulate growth: a high protein quality, bioavailable minerals that are important for growth, and perhaps lactose. Higher adult stature is associated with both positive and negative health effects. Growth stimulation is important in populations with undernutrition, but in well-nourished populations, it might not be important. A high intake of cow's milk and thereby a high protein intake early in life can increase the risk of later overweight and obesity, while a high protein intake later in childhood seems to be associated with a lower BMI later in childhood. A high dairy intake can limit the diversity of the diet and result in iron deficiency. Therefore, milk intake should not exceed 500 mL/day in young children. Most products for the treatment of undernutrition include dairy protein because of the well-documented effects on growth and recovery. However, as dairy is an expensive ingredient, the amount needed and the effects of alternative plant-based protein sources are considered.