Two experiments examined how different frustration contexts affect the instrumental and emotional responses of 4- to 5-month-olds. Both experiments showed that arm responses increased when the contingent stimulus was lost or reduced but decreased when control of the stimulus was lost under noncontingency. Facial expressions of anger, but not sadness or combined anger and sadness, were associated with frustration. Patterns of anger and arm responses varied with frustration context. (Author/KB)