tion is needed in order to produce measurable improvements in children 's developmental outcomes.
Finally, with welfare reform has come a growing interest in the families of the working poor. This vast natural experiment has also created new opportunities to learn about how various approaches to increasing work and income among families living in poverty affect both child and adult outcomes of paramount interest to the nation. Increasingly, research addressing questions about how resources change over time and their impact on children's development is relying on longitudinal data and experimental designs.
Understanding how different family resources affect young children 's lives necessitates distinguishing among them; connecting them to such resources as money, time, and access to the learning opportunities that they represent; and identifying the different pathways through which these resources might influence young children's development. Taking poverty as an example, it is important to know how it manifests itself in young children's lives, how it affects the extent to which their basic needs are met, and through what processes it promotes or undermines their capacity to accomplish the basic developmental tasks outlined in the previous chapters of this report.
It would be surprising if the odds of healthy, adaptive development did not differ for children growing up in families with ample, compared with impoverished, resources. Families who occupy different socioeconomic niches because of parental education, income, and occupation have strikingly different capacities to purchase safe housing, nutritious meals, high-quality child care, and other opportunities that can foster health, learning, and adaptation (Becker, 1981; Brooks-Gunn et al., 1995). A two-parent family with one highly paid wage earner who makes it possible for the other parent to stay at home with the children is in an entirely different situation from a single parent with a poverty-level wage, for example (Becker and Lewis, 1973; Mason and Kuhlthau, 1992; Timmer et al., 1985). How the trade-offs that families make among employment, cash income, and child care time affect young children is a controversial and poorly understood question.
The psychological well-being of mothers and associated patterns of parenting are also much more likely to suffer in families with limited resources (Brooks-Gunn and Duncan, 1997). Research has focused increasingly on connections among family resources, psychological aspects of family functioning, and child well-being (McLoyd, 1998). Finally, there is growing interest in how families' access to different social resources, such