The first section of this article traces the evolution of the social isolation construct over the last three decades and concludes it is not one etiologic factor for child maltreatment, but a large set of variables linked to the parents' perception of support, and their informal and formal networks. The empirical section examines each component of the social isolation construct by comparing 300 maltreating and nonmaltreating low-income mothers. Considerable variation was found between the networks of different types of maltreating mothers and nonmaltreating mothers on structural network properties, perception of support, and the types of resources they do and do not receive. For example, neglectful mothers had fewer network members, fewer contacts, fewer members living within 1 hour, and received fewer emotional and instrumental resources. Despite these findings, the label social isolation may not accurately describe the networks of mothers who maltreat their children, since all three types of maltreaters had at least eight important network members and more than 100 contacts with these members in the month before completing the questionnaire. Tables, references