As Theravāda Buddhist thought developed, there was a tendency to elaborate on the original teachings through the proliferation of scholastic categories. Two categories developed to lend analytic precision to the concept ofkamma are those of undetermined (aniyata) and indeterminate (avyākata)kamma. This paper analyzes these two concepts as developed in theTipiaka and clarified in theAtthasālinī. As Theravāda Buddhist thought developed, there was a tendency to elaborate on the original teachings through the proliferation of scholastic categories. Two categories developed to lend analytic precision to the concept ofkamma are those of undetermined (aniyata) and indeterminate (avyākata)kamma. This paper analyzes these two concepts as developed in theTipiaka and clarified in theAtthasālinī.