Facial, body, and cry behaviors, heart rate, palmar sweating, and acoustic cry measures were compared across differing levels of infant pain. Eighty-eight infants were placed in a 16-cell matrix of 4 ages (0 to 3 mo., 4 to 6 mo., 7 to 9 mo., and 10 to 12 mo.) and levels of pain (LOP) (none, mild, moderate, severe) with 5 to 6 infants occupying each cell. Matrix placement was determined by agreement of > 75% among five pediatric clinical nurse specialists who viewed videotapes and read information about the infant's history, diagnosis, medical and/or surgical status, medications, and nutritional/fluid status. Coded infant behaviors and acoustic cry parameters were compared using a 2-level (LOP, age) MANOVA. Behaviors that differed across LOP were influenced by infant development. Facial expressions were clinically useful LOP indicators only for 0- to 3-month-old infants. Facial and body behaviors and cry measures that differed across LOP in younger infants did not differ in older infants due to the development of intentionality. Cry orientation and consolability may be useful clinical indicators of pain with older infants.