Although it is often assumed that men have an important influence on their children's development, the supportive evidence can be difficult to locate and summarize. In this paper, we analyse the evidence with respect to four emergent themes. First, men often appear to interact with their children less sensitively than mothers do, and many children thus appear to form closer attachments to their mothers than to their fathers. Second, the data also indicate that fathers may play specific and important roles, with men in some cultures having clearly defined roles as playmates to their children. Third, paternal play styles predict later socio-emotional development while paternal involvement seems to predict adult adjustment better than maternal involvement does. Such evidence suggests, fourth, that we need appropriate measures of fatherhood that are not simply borrowed from the study of motherhood.Thirty years ago, fathers were described as 'forgotten contributors to child development' (Lamb, 1975). Since then, men have been in and out of the research focus, but there is now a large database with which to assess the roles of men in families. For the past 15 years, more than 700 articles on fathers have been cited each year in the Psychological Abstracts database. Although we assess current research on the nature and importance of father-child relationships in this paper, therefore, we must acknowledge from the outset that a brief review can only sketch the broad outlines particularly as the study of fatherhood has become so complex and multi disciplinary. Readers are referred elsewhere for more complete summaries of the recent research (Day & Lamb, in press; Lamb, in press;Tamis-LeMonda & Cabrera, 2002). In the interest of simplicity and brevity, we confine our analysis to research on two-parent households.We argue here that, when two parents live with their children, fathers contribute to their children's development in important ways. Not only should we take men into account when studying families [as do the other papers in this special edition], but we should also consider