The article discusses how different decision-making groups work together in polycentric governance systems. It looks at how the decisions made in one group can affect another group, either helping or hindering how well the members can achieve their goals. By studying two specific areas, the California Delta and Tampa Bay watershed, they found that these interactions, known as externalities, have a mixed impact. In the California Delta, externalities tended to make things harder for the members, but in Tampa Bay, there was no clear effect. The study also revealed that how well members perform in one group can change how much impact these externalities have on their performance in the other group. For those who don't do well in the first group, externalities tend to harm their success in the second group, but if they perform better in the initial group, the negative impact lessens.