The onset of 12 milestones that occur from 6 to 24 months of age was studied in premature and full-term infants. The milestones are: sitting, crawling, teething, walking, pursuit of a hidden sound-making object, stranger anxiety, separation anxiety, "no" gesture, words, phrases, speech "no," and speech "yes." It was hypothesized that premature infants would show delay in acquiring milestones related to time separated from mother. Compared to full-terms, the prematures had no significant difference in the means for the onset of the milestones except for: sitting, crawling and walking related to maternal separation; and crawling and teething, related to birth weight.