This study used a micro-trial design to evaluate ‘Lou & us’, a 3-week parenting program based on metacognition. The program consists of sessions using a CD-Rom and interviews with the program deliverer. The study tested whether and to what extent the program is effective in enhancing positive parenting, in particular childrearing behavior, self-efficacy beliefs and co-parenting. In Study 1, the program was used by French-speaking mothers and fathers in a community-based sample of 152 families. Study 2 was a randomized control trial in which the program was used by French-speaking mothers and fathers from 58 families out of the 116 involved. In Study 1, ‘Lou & us’ was found to increase supportive parenting, reduced controlling parenting, and increase fathers’ self-efficacy beliefs. The results of Study 1 were partially replicated in Study 2. Furthermore, the intervention was seen to enhance co-parenting for both mothers and fathers, as well as their assessment of their children’s externalizing behavior. The findings suggests that a limited number of activities based on the core process of metacognition and delivered in a limited period of time can be effective components for enhancing positive parenting.