Research is a collaborative effort. Most of the time, we are not writing papers alone but together with others. Sometimes we lead the effort, sometimes we are the second author, sometimes we only have a small role to play. Coauthoring papers often leads to tensions, frustrations and disappointments. Are there any rules about co-authorship? We think there are. We give you four rules about how to be the best co-author. As usual, the references to readings we mention are listed on .