In this paper, we present a usage-based study to constituent ordering in Persian in line with studies on word order variations that take into account functional factors. The results of our empirical study, combining corpus-based and experimental data, goes against the widespread theoretical view of Persian’s phrase structure. More precisely, our results undermine the backbone argument put forward to support this view which consist of a broadly admitted claim regarding the relative order between objects in a ditransitive sentence. Persian is an SOV language with DOM triggered by definiteness and/or specificity and marked by the enclitic =rā, (1). This enclitic is also used as a topicalizer, placed in the initial position, beyond DO, (2). It should be noted that Persian do not formally mark nouns for definiteness, a single noun without any formal determination, ketāb, can receive two reading (except in the DO position): 1) bare noun, that is, a noun lacking any determination or quantification, nonspecific and under-specified for number, ‘a book, some books’; 2) definite noun ‘the book’. (Existential) indefiniteness is, however, formally marked by the determiner ye(k), ye ketāb, the enclitic =i, ketāb=i, or the combination of both, ye(k) ketāb=i, ‘a book’. Furthermore, disposing only of around 250 simplex verbs, verbal concepts are mainly expressed in Persian by complex predicates (cf. Samvelian 2012), that is the combination of a simplex verb and a non-verbal element, prototypically involving bare nouns (dars xāndan ‘to study’), (2). (1) a. Maryam ketāb xarid Marya book bought-3SG ‘Maryam bought a book/some books.’ b. Maryam ketāb=rā xarid Maryam book=DOM bought-3SG ‘Maryam bought the book.’ (2) tābestān=rā dars mi-xān-am summer=DOM lesson IPFV-read.PRS-3SG ‘Summer, I will study.’ Most theoretical studies, namely in the framework of the generative grammar, postulate a phrase structure for Persian reflecting a structural asymmetry between rā-marked and non-rā-marked DOs (e.g. Brown & E. Karimi 1994, Ghomeshi 1997, Karimi 2003, 2005). Despite their substantial difference, these studies posit two different positions, either base-generated or resulting from a movement, for rā-marked vs. non-rā-marked DOs, roughly represented in (3). Furthermore, they share the same methodological approach, based mainly, if not exclusively, on the authors (categorical) grammaticality judgments. (3) a. [VP DP[+rā] [V’ PP V]] b. [VP [V’ PP [V’ DP[-rā] V]]] Karimi (2005) provides the most thorough argumentation in favor of this analysis. Considering rā-marking a matter of specificity, the author assimilates non-rā-marked DOs, to bare nouns, minimizing their significant differences, and puts forward a number of observations suggesting syntactic and semantic asymmetries between rā-marked and bare DOs to support this analysis. Namely, the semantic incorporation of non-rā-DOs into the verb, similar to the combination involved in CPs, and their lack of (semantic and syntactic) autonomy contrary to rā-marked DOs, and the unmarked word order between the DO and the IO, which is, broadly assumed to follow the schema in (4). (4) a. DO[+rā] IO V b. IO DO[-rā] V Adopting a truly empirical approach, we have studied the relative order between the DO and IO in Persian in line with studies on word order preferences (e.g. Hawkins 1994, Arnold et al 2000, Yamashita & Chang 2001, Wasow 2002, Bresnan et al 2007). Including a preliminary multifactorial corpus study and follow up (off-line) psycholinguistic experiments conducted via web-based questionnaires, our study takes into account functional factors shown to play significant role in word order preferences cross-linguistically such as length, givenness, humanness, verbal lemma, via mixed-effect regression modeling. Most importantly, our results show that the oversimplifying dual classification of DOs based on markedness is flawed: in comparable context, while rā-marked DOs show a strong preference for the DO-IO order and bare DOs for the inverse, the picture is less clear-cut for in-between DOs. In one hand, indefinite/quantified (non-rā-marked DOs) - contrary to what is expected by the theory - show a clear preference, although moderate, for the DO-IO order, grouping with rā-¬marked DOs. In the other, bare DOs carrying adjuncts, show a much less strong preference for the IO-DO order. More generally, extra-syntactic factors such as relative length and humanness show up to play a significant role. Indeed, ordering preferences between the DO and the IO, rather than being dichotomous, are best reflected by a continuum based on the degree of determination of the DO - closely related to its discourse accessibility (cf. Gundel et al. 1993) - as well as other (functional) factors related to the conceptual accessibility, such as relative length (cf. Yamashita & Chang 2001) and humanness. Furthermore, examining all other arguments put forward, we conclude that there is no empirical ground for positing two syntactic positions for the DO. Accordingly, the dual phrase structure analysis for Persian that provides wrong predictions with respect to the unmarked word order is refuted. This study thus highlights the importance of using empirically solid methods in theoretical syntax.