This note comments on Bruni and Sugden's interesting notion of fraternity among contract partners as joint commitment to cooperate for mutual benefit. I raise two points on their paper, both concerning the role of sacrifice. First I maintain that, differently from other social preferences, guilt aversion does not imply self-sacrifice. Secondly, I argue that aiming for mutual benefit does not prevent individuals from facing trade-offs between their own and their partners’ surplus, so the notion of sacrifice cannot be entirely eschewed. (...) To the contrary, reciprocal ‘sacrifices’ enhance cooperative intentions and help create feelings of friendliness. (shrink)