Solidarity and Prosocial Behavior 18 it was one of the O.P it was one of the purposes of the symposium to investigate both similarities and thp differences has received more attention than the "first method" The topics of so darity and prosocial behavior are at the core of both disciplines and thus one might expect that an intensive cooperation like the one that produced this book is not uncommon The conviction that sociology and psychology can benefit from each other’s work led us—a group of sociologists and psychologists at the University of Groningen (The Netherlands)—in 1999 to launch a joint research project on solidarity and prosociality