Throughout the history of child development, the family has played a ubiquitous role in theory, research, practice, and policy aimed at understanding and improving child welfare and development. From grand theories to heated controversies, family processes and roles have been invoked in numerous ways in developmental science over the past century to explain or debate whether and how families matter (Collins, Maccoby, Steinberg, Hetherington et al., 2000; Maccoby, 1992). Psychoanalytic theory (Freud, 1933/1964; Munroe, 1955), attachment theory (e.g., Bowlby, 1969, Carlson & Sroufe, 1995; Sroufe & Waters, 1977), ecological and developmental systems theory (e.g., Bronfenbrenner, 1979, Ford & Lerner, 1992; Sameroff, 2000), family systems theory (Davies & Cicchetti, 2004; Fiese, 2000; Fiese & Spagnola, in press), social learning and social cognitive theory (Bandura, 1977, 2001; Gewirtz, 1969), coercion theory (e.g., Patterson, 1982), parenting styles theory (Baumrind, 1967, 1973), and a variety of other influential frameworks have emphasized the family in diverse ways. Theories about the origins of competence and about the origins of psychopathology also have focused on family roles and processes (Cummings, Davies, & Campbell, 2000; Fiese, Wilder, & Bickham, 2000; Masten & Coatsworth, 1995; Masten, Burt, & Coatsworth, in press).