The links between parents’ emotion regulation practices and children’s behavioral outcomes are well established. The aim of the current study designed as a randomized micro-trial was to test experimentally if and to what extent stimulating parents’ emotion coaching practices improves preschoolers’ behavioral outcomes, i.e. positive affect, irritability, non-compliance, persistence and enthusiasm. In line with this objective, the emotion coaching practices of parents of 4-to-5-year-old children were stimulated in a brief 15-min lab session. Immediately afterwards, parents and children were observed during a free-play session and frustration laboratory tasks designed to elicit negative emotions in children. The results indicated that, compared to the control group, parents whose emotion coaching practices had been stimulated displayed higher positive affect and were more emotionally sensitive during free play. Positive behaviors persisted in frustration tasks; parents were more behaviorally and emotionally responsive towards their children. In turn, children of these parents displayed higher persistence and enthusiasm but only when they had to deal with negative emotional arousal during frustration tasks. Mediation analyses also confirmed that the influence of the stimulation of parents’ emotion coaching practices on children’s outcomes, i.e. persistence and enthusiasm, was mediated by the parents’ behavior.