The study presented in this book focuses on the acquisition, maintenance and change of Differential Object Marking (DOM) in Spanish, English and Romanian in contact with English in the United States. Differential Object Marking (DOM) is the overt marking of some direct objects and is a widespread among languages of the world. DOM is an iconic procedure because the arguments that are overtly marked morphologically are more salient/prominent semantically or pragmatically than unmarked objects. This chapter describes how DOM is manifested in Spanish, Romanian and Hindi and presents current syntactic synchronic analyses of the phenomenon in these languages. The diachronic evolution of DOM in language contact situations is also discussed.