|Abstract:||There is significant variation in patterns of object marking in Bantu languages. When object markers occur, their distribution depends on syntactic, semantic, and discourse factors. This paper develops an analysis in Optimality Theory of variation in object marking along three parameters: doubling, multiplicity, and symmetry. Both single- and double-object constructions are analyzed, with variation in the form of the object: in-situ lexical object, pro, and a displaced topicalized object. The structure of the typology is then analyzed with Property Theory (Alber and Prince prep; Alber et al. 2016; DelBusso 2018), identifying the central constraint conflicts that define the grammars and determine the traits of the languages. For example, there is a property whose values separate all language allowing multiple object markers from those allowing only a single object marker. Each of these groups is further divided along additional parameters. The different object marking patterns result from different sets of property values.