IntroductionSpanish and Romanian, among Romance languages, exhibit a systematic combination of two different devices for object marking, i.e. Clitic Doubling (hereinafter, CD) and Differential Object Marking (hereinafter, DOM). In this paper I will discuss mostly Spanish 2 data, with the aim of focusing on the well known specificity constraints that hold both in CD and in DOM, and offering an account of their similarities and differences. I will restrict my attention to direct object CD; moreover, I will assume that