There is a paucity of information on whether and how the composition of formulas fed to infants influences their short-term feeding behaviors during the first few months of life. The purpose of this study is to investigate whether the composition of infant formula affects infants' feeding behaviors, in particular, how much formula is consumed within a given feed (i.e., measure of satiation) and how much time elapses after the feed until the infant exhibits signs of hunger (i.e., measure of satiety). The investigators will also examine the relationship between the composition of infant formula consumed and infant temperature, activity, sleep, and mothers' perceptions of infants' intake and regulatory behaviors.

This is a within-subject, 3-day study. Each mother-infant dyad will visit the Monell Center three times, for 5 hours each time. The protocol during the three visits will be identical. Upon arrival, the infant will be changed into a light-weight cotton body suit. Infants and mothers will be weighed and measured for height. An activity sensor will be placed on the infant and temperature sensors will be placed on both the infant and the mother. When the infant signals hunger, he/she will be fed one of three formulas in randomized order:

1. cow milk based-formula (Enfamil)
2. protein hydrolysate formula (Nutramigen)
3. cow milk-based formula with glutamate level similar to Nutramigen (Enfamilg)

Intake will be monitored and all feeds will be videotaped. In between feedings, infants will rest or sleep on their backs in a crib and mothers will fill out questionnaires.

Inclusion Criteria:

• Healthy, term infants of any racial background
• Infants may be of either sex
• Infants must be between 1 and 4 months of age
• Infants must be exclusively feeding a cow's milk-based formula
• Mothers must be over 18 years of age

Exclusion Criteria:

• Infants who were preterm
• Infants who have medical conditions that interfere with feeding or eating
• No major complications during pregnancy or at birth

Mothers with healthy infants who are between the ages of 1 to 4 months and are exclusively feeding cows milk-based formulas will be recruited from the Philadelphia area for this within-subject experimental research study.