Data were collected from students in grades three to eight (N = 377) in order to identify the determinants of their intentions to perform laboratory and nonlaboratory science activities. Fishbein and Ajzen's theory of reasoned action was used as the basis for the study. The theory posits that the immediate determinant of behavior is intention. Intention is determined by the weighted attitude toward the behavior and the weighted subjective norm. Attitude toward behavior and subjective norm are determined by combinations of beliefs, evaluations, and motivations to comply. Cores of salient beliefs related to attitude toward laboratory and nonlaboratory behaviors and cores of salient beliefs related to subjective norm for laboratory and nonlaboratory behaviors were identified. Hypotheses generated from the theory were confirmed. Attitude toward behavior and subjective norm explained significant amounts of variance in behavioral intention for both laboratory and nonlaboratory behaviors. Attitude toward behavior had a greater relative weight than subjective norm for both laboratory and nonlaboratory. The correlations between adjacent constructs in the theoretical model were significant in all cases.