This research compared the efficacy of two parenting interventions that vary according to the number and the nature of variables in reducing preschoolers' externalizing behavior (EB). The goal was to identify which parenting intervention format (one-variable versus two-variable) caused higher behavioral adjustment in children.

The first format was a one-variable intervention manipulating parental self-efficacy beliefs. The second format was a two-variable intervention manipulating both parents' self-efficacy beliefs and emotion coaching practices. The two interventions shared exactly the same design, consisting of eight parent group sessions. Effect on children's EB and observed behaviors were evaluated through a multi-method assessment at three points (pre-test, post-test and follow-up).

Inclusion Criteria:

• children in the clinical or borderline range of the EB scale (cut-off = 21 or higher) of the Child Behavior Checklist preschool form (Achenbach & Rescorla, 2000a)
• three to six years old and still in kindergarten at the beginning of the intervention

Exclusion Criteria:

• children with intellectual disabilities (average IQ < 5.5)
• highly gifted children (average IQ >14.5)