The study examined the effect of the behavioral approach and inhibition systems, derived from Gray's theory, on the construction process of the positive and negative valenced categories in positive and negative mood conditions. The experiment was conducted. Initially, participants completed a questionnaire covering BIS and BAS systems (Carver & White, 1994). They were then randomly assigned to either a positive or negative experimental mood conditions. Based on the group they were placed in, after mood induction procedure and completing a questionnaire of current mood state, the participants then categorized the given material (ambiguous sentences). The results showed that mood state didn't have the effect on categorization process. The emotional content of the created categories was mainly related to the interaction between mood state and individual differences in BIS and BAS systems. The high BIS as well as high BAS scores were related to emotionally biased categorization. This result was mainly observed in the negative mood conditions. However, individuals scored high in BAS scale were oriented toward negative as well as positive emotional meaning of the categorized objects. Whereas the orientation of the high BIS scored subjects was primarily biased toward negative meaning of objects. Obtained results suggest that the affective orientation toward positive and negative emotional stimuli may play a different regulative role among high Bis and high Bas individuals. Furthermore, the high Bas individuals seem to have more flexible affective orientation than the high Bis individuals.