A series of experiments involving speech dysfluencies of normal, adult speakers is presented and evaluated in light of earlier work on the conditioning of dysfluencies in a punishment paradigm. The data suggest that the dysfluencies of normal speakers can be systematically manipulated in a variety of ways, ranging from specific punishment procedures to changes in general situational variables. When the variety of studies is reviewed in which dysfluencies have been altered in experimental situations, it appears that three major variables emerge: the speaker's perception and evaluation of the situation in which he is performing; the speaker's history of experiences with nonfluencies in earlier, similar situations; the nature and arrangement of the contingent stimulus. Some comparisons between stutterers and normal speakers are tentatively advanced in a final section.