Studies have shown that infants of depressed mothers express negative emotions more frequently than infants of nondepressed mothers. The present study examined electrical brain activity during expression of negative and positive emotions in infants of depressed and nondepressed mothers. Infants, 11 to 17 months of age, were exposed to conditions designed to elicit positive and negative emotions while electroencephalographic (EEG) activity was measured from left and right, frontal and parietal regions. EEG activity was analyzed when infants were displaying prototypic expressions of emotions. Compared with infants of nondepressed mothers, infants of depressed mothers exhibited increased EEG activation in the frontal but not parietal region when expressing negative emotions (unfelt smiles and anger). The two groups of infants did not show reliable differences is brain activation during the expression of positive emotions (happiness, surprise) or neutral expressions. Compared with infants of nondepressed mothers, infants of depressed mothers exhibit greater frontal EEG activation during the expression of negative emotions.