A study was undertaken on the effects of a specific parent administered infant language stimulation program, beginning at birth, on the longitudinal development of 60 normal first born infants. All infants and their environments were tested in their homes at 6 weeks and at 6 months utilizing the Bayley Scales of Infant Development and the HOME Inventory. The Ss were divided into three groups (control, mothers receiving the program, and both mothers and fathers receiving the program). All groups showed an increase in the Bayley Mental Standard Scores, with infants whose parents both received training exhibiting the greatest gain over time. HOME scores, which measured the adequacy of the home environment, showed a training effect improvement, but the two groups did not differ significantly from each other. It was concluded that the program may benefit all children, and that parents of first born children would benefit from preparation and assistance in helping their child achieve maximum potential. (Author/PHR)