Attachment theory predicts that maltreated children will form insecure patterns of attachment to their caregivers and that attachment relationships are open to change with development. In this cross-sectional/longitudinal investigation, we examined the attachment patterns of 125 maltreated and nonmaltreated preschoolers from the low socioeconomic strata (SES). Maltreated and demographically matched nonmaltreated comparison children were assessed in the Strange Situation at 30, 36, and 48 months of age, along with a subsample of children who were observed longitudinally across a 6- to 18-month period. Attachment relations were classified using a newly developed system for assessing attachment in the preschool years by Cassidy and Marvin (1991). Results revealed that, at each age, maltreated children were significantly more likely to evidence insecure patterns of attachment to their caregivers. The specific types of insecurity demonstrated by children varied with age. Longitudinally, the high percentage of nonmaltreated children who were classified as securely attached were likely to remain securely attached at subsequent assessments. In contrast, the small number of maltreated children who evidenced secure attachments were unlikely to be classified as secure at later assessments. These data provide new information on the patterns of attachment maltreated children exhibit in the preschool years.