The multicomponent interventions also meet standards for evidence-based treatments at least in middle class mothers and in the short term. One intervention was designed based on family systems theory [Pelchat et al., 1999]. It was the only study in this synthesis that attempted to address some of the needs of siblings and other family members while primarily focusing on the parents of infants. When more complex intervention methods were presented to parents over a relatively longer period of time than in the single component studies, there were substantial reductions in parental distress. The five studies with multiple component interventions had an average unweighted effect size of d 5 0.90 is very close to the average effect sizes for studies in the general psychotherapy literature when treatment groups were compared to no-treatment comparison groups (d 5 0.82) and exceeds the average effect size when treatments were compared with a placebo (d 5 0.48) [Wampold et al., 1997].