The efficacy of small group instructional programs in classificatory, seriation, and combined class/series skills was evaluated for a sample of 60 urban, middle-class, 4- to 5-year-old children in a transfer of training design. Significant curriculum-specific transfer effects were found for the seriation instructional condition, whereas little differences were found for the classification, verbal intelligence, and far-transfer conservation task measures. Sex differences, school location effects, teacher biases, and pretesting effects were generally absent. The apparent feasibility of seriation skill instruction for preschool-aged children and the general noneffectiveness of the classificatory and combined instructional conditions, particularly insofar as far-transfer effects are concerned, suggest a nonunitary picture of cognitive functioning during the transitory phases between preoperational and concrete operational period thought. (Author)