ABSTRACTThis paper begins with the assumption that it is morally problematic when people in need are offered money in exchange for research participation if the amount offered is unfair. Such offers are called ‘coercive’, and the degree of coerciveness is determined by the offer's potential to cause exploitation and its irresistibility. Depending on what view we take on the possibility to compensate for the sacrifices made by research participants, a wish to avoid ‘coercive offers’ leads to policy recommendations concerning payment (...) for participation. For sacrifices considered compensable, we ought to offer either no payment or payment at a level deemed fair, while for sacrifices deemed incompensable, we always ought to offer no payment because as compensation appears and increases, so too does coercion. This article provides a model for thinking of the way in which degrees of exploitativeness, irresistibility, and coerciveness interact with the size of the reward for compensable and incompensable cases. T... (shrink)