Infant formulas provide the essential macro- and micronutrients a child needs to meet their dietary requirements, especially those unable to meet these needs through breastfeeding. This chapter explores key considerations for choosing both infant and pediatric formulas, focusing on the diverse range of options available in order to meet the nutritional needs of the infant or child. This chapter also discusses the options to transition from infant formula, either to a milk or milk alternative, or if needed, a pediatric formula, and factors to consider during this transition. Certain disease states require the use of specialty formulas, designed to address specific metabolic, digestive, or growth-related concerns. Conditions such as premature birth, inborn errors of metabolism, gastrointestinal disorders and food allergies may impair nutrient absorption or utilization, which then necessitates tailored nutrition support. Ultimately, this chapter will provide guidance for clinicians on selecting the most appropriate feeding option to support healthy growth and development in the infant or child.