Explored preschoolers' solitary-active play in the presence of peers as a marker for maladjustment among 153 children. Found that, compared to peers, children with frequent solitary-active behaviors were temperamentally less attentive, were more difficult to soothe, behaved more shyly, displayed more externalizing problems, performed more poorly on assessments of academic skills, and had a less positive attitude toward school. Found no differences in receptive vocabulary. (Author/KB)