In two separate publications, the average patterns of, and individual differences in, preschoolers' selective attention processes were investigated using a multilevel modeling framework. In Publication 1, using two independent samples (Ns= 42, 75), preschoolers' selective attention towards different types of emotions (both positive and negative) was examined using two eye-tracking tasks. The results showed that, on average, children selectively attended to valenced emotional information more than neutral emotional information. In addition, a majority of children were able to detect the different emotional stimulus among three neutral stimuli during the visual search task. Children were more likely to detect angry than sad emotional expressions among neutral faces; however, no difference was found between detection of angry and happy faces among neutral faces. In Publication 2, the associations of children's anger and sadness proneness to their attention biases towards anger and sad emotional information, respectively, and the relations of these biases to various aspects children's social functioning and adjustment were examined among preschool-aged children (N = 75). Children's predisposition to anger and sadness were shown to be related to attentional biases towards those specific emotions, particularly if children lacked the ability to regulate their attention. Similarly, components of attention regulation played an important role in moderating the associations of biases towards angry information to aggressive behaviors, social competence, and anxiety symptoms. Biases towards sadness were unrelated to maladjustment or social functioning. Findings were discussed in terms of the importance of attention biases and attention regulation as well as the implications of the findings for attention training programs.