This study examined the role of friendship jealousy and satisfaction in nine-year-old children's observed interactions with their best friends. One hundred five dyads (51 female, 54 male) participated in a 30-min closed-field observational setting and reported their jealousy and satisfaction within the friendship. The Actor–Partner Interdependence Model was used to estimate the effects of friendship jealousy and satisfaction on children's own and their friends' behavior. Friends were highly similar in observed behavior and friendship characteristics. Many observed dyadic behaviors were associated with overall levels of jealousy within the friendship, but differences in friendship satisfaction were only predictive of conflict resolution in boys. Children's reports of their friendship jealousy were strongly related to their own behavior in the dyad and the behavior of their best friends. Gender differences were discussed. The results further illustrate the importance of a dyadic perspective on friendship interaction.