Is early preventive intervention effective in enhancing parental sensitivity and infant attachment security, and if so, what type of intervention is most successful? Seventy studies were traced, producing 88 intervention effects on sensitivity (n = 7,636) and/or attachment (n = 1,503). Randomized interventions appeared rather effective in changing insensitive parenting (d = 0.33) and infant attachment insecurity (d = 0.20). The most effective interventions used a moderate number of sessions and a clear-cut behavioral focus in families with, as well as without, multiple problems. Interventions that were more effective in enhancing parental sensitivity were also more effective in enhancing attachment security, which supports the notion of a causal role of sensitivity in shaping attachment.

The current meta-analytic study focuses on the analysis and synthesis of sensitivity and attachment interventions. Experimental intervention studies that aim at changing parental behavior or children's development are important at least in two ways. First, nonexperimental research designs seem to dominate the field of parenting and child development, and much of the knowledge about parenting and development is derived from descriptive cross-sectional or longitudinal studies. However, experiments may be crucial in determining whether parenting is indeed causally related to child development or whether genetics or nonparental influences are the most powerful force in shaping children's development (Harris, 1998; Rowe, 1994). In this respect, the field of attachment research may serve as an example. Descriptive attachment studies outnumber by far experimental investigations, although their central hypotheses are formulated in causal terms, such as the alleged causal association...