​This paper investigates the clause structure of periphrastic tense constructions with two fully inflected auxiliary and lexical verbs. The recent accounts of the syntax of tense assumes that the semantic categories of time; the time of utterance, the topic time, and the time of situation, are syntactically mapped into the clause structure of these constructions (Giorgi and Pianesi, 1997). Previous accounts of the syntax of these constructions in Arabic assume that they are biclausal with two TPs (Fassi Fehri, 2004). Contra to these accounts, we contend that these constructions in Standard Arabic are monoclausal with an embedded AspP and not biclausal with two TPs. The lack of two TPs is supported by independent semantic and morphosyntactic evidence such as the impossibility of distinct temporal modification and the unacceptability of embedding a tensed negative particle. However, the potential recursion with two vPs and two independent AspPs is supported by the possibility of allowing two independent subjects and the availability of two fully aspectual and agreement inflections on both verbs, respectively.​