"A Dilemma For Jeffrey Conditionalizers" Abstract: A rule for updating degrees of belief should be commutative: if the same total information is gleaned then the same degrees of belief should result, regardless of the order in which the information is learned. Commutativity is an old worry for Jeffrey Conditionalization, since the order in which values are put into the rule makes a difference to the end result. The worry seems to have been resolved in recent work by Lange (2000) and Wagner (2002). But I argue that, to resolve the commutativity problem we must give up another important desideratum on updating rules: holism. Holism requires that the effect sensory input has on one's corpus of beliefs be sensitive to one's background beliefs. When an object looks red, whether or not we should judge that it is red depends on what we think about the lighting, the reliability of our vision, etc. Since preserving commutativity means giving up holism, proponents of Jeffrey Conditionalization face a troubling dilemma: they may have commutativity or holism, but not both.