Investigated longitudinally were individual differences in 1- and 2-year-olds' exploratory behavior and their relationship to problem-solving ability. Of particular interest was the stability of exploratory and problem-solving behaviors across the second year of life. It was expected that stability of exploratory behavior would be found in terms of its level in cognitive sophistication rather than in identical behaviors at year 1 and year 2. It was further expected that the variety of different schemes used during exploration at 1 year of age would be related to success and sophistication in problem-solving in the second year. Subjects, from predominantly white and middle-class families, were observed when 26 to 29 months of age in their homes; 15 male and 14 female subjects constituting the longitudinal sample had been observed previously in an infant research laboratory when the children were 1-year-olds. Findings are at least suggestive of some stability of infants' exploration and problem-solving behaviors over the second year of life. As hypothesized, 1-year-old infants who used a greater number of different schemes during exploration were found to be more successful and sophisticated in problem-solving at the age of 2 years. (RH)