The determinants of fourth, fifth, sixth, seventh, and eighth graders' intentions to perform science learning activities were investigated. Ajzen and Fishbein's theory of reasoned action was used to assess students (n ϭ 254) on their laboratory and nonlaboratory behavioral intentions, which required using the two determinants included in the theory (attitude toward the behavior and subjective norm) as well as five external variables identified by the researcher. The five external variables were gender, grade, race/ ethnicity, socioeconomic status as determined by the range of the family's annual income, and attitude toward science. Two models were tested. The first model included the two determinants as predictor variables and behavioral intention as the criterion. The second model involved the analysis of the two determinants as they were considered in subgroups according to the five external variables. This model also included interaction terms. For laboratory learning activities, the two determinants (attitude toward behavior and subjective norm) were found to contribute collectively to the prediction of behavioral intention, accounting for almost a fourth of the variance. For nonlaboratory learning activities, the two determinants accounted for over a fourth of the variance in behavioral intention. Testing of the second model revealed that for both laboratory and nonlaboratory behavioral intentions, no interaction terms were significant. The results of post hoc tests on significant predictors of behavioral intentions for laboratory and nonlaboratory activities are reported. Implications of this study on future research are also discussed.