This paper aims to partially verify the hypothesis following which the grammaticalisation of the Ibero-Romance
future and conditional tenses unfolded earlier in the (north-)eastern peninsular varieties before spreading to the central and
western part of the Iberian territory through language and dialect contact. For this purpose, we will contrastively examine the
distribution of futures and conditionals in Navarro-Aragonese and Castilian for the 13th and 14th century, more specifically the
variation between the so-called synthetic verb forms with postverbal object pronouns and the analytic forms with mesoclitic
pronouns, including the morpho-syntactic factors that favour the use of the former. It is shown that Navarro-Aragonese seems to
exhibit a higher frequency of use of the synthetic forms with postverbal pronouns, especially with syncopated verbs, conditionals
and a following non-finite verb form.