This study examined the effectiveness of a training program designed to help disadvantaged teenage mothers promote their infants' early cognitive development. Subjects were 127 mothers whose babies were less than 6 months old at the start of the program; most were white women near the poverty level, and many were unmarried. The control group consisted of 171 mothers classified into three subgroups according to their level of motivation, as indicated by degree of participation in the program. In the experimental program mothers attended 3-hour sessions for 10- to 12-weeks. Sessions focused on infant and child management techniques and practical teaching skills. A second component involved the mailing of supplemental booklets to participants every 2 months until their children were 48 months old; the booklets, written at sixth grade reading level, offered suggestions for progressively more complex mother-infant interactions. It was hypothesized that by the time the children were 3 years old the training program would result in significant differences in cognitive development between the experimental and control groups; as measured by the Bzoch-League Receptive-Expressive Emergent Language Scale, the Utah Test of Language Development and the Bayley Scales of Infant Development. Results of the program after 12 months and 24 months are reported. (BF)