The main purpose of this paper is to analyse formal and functional aspects of constructions based on a Justification (or Claim-Argument) coherence relation, explicitly marked by a connective. The prototype of this construction is an utterance like Está gente em casa, porquer as luzes estão acesas [“ There is somebody at home, because the lights are on”]. The empirical data are collected from an on-line corpus of contemporary written Portuguese (CETEMPúblico). Following Sanders et al.(2001), I assume the distinction between semantic and pragmatic coherence relations in text representation: Semantic relations connect the situations of the sociophysical world described by the propositional content of the related textual segments; pragmatic relations involve the illocutionary domain, i.e., the relation concerns the speech act status of the segments. Justification relation is a pragmatic relation and I argue that it requires simultaneously a sequence of speech acts and an inference process. In fact, Justification relations occur typically in argumentative contexts, and argumentation, according to van Eemeren & Grotendorst (1984), is a compound illocution, consisting of at least two functionally distinct statements: A main assertion corresponding to the claim being made and a subordinate assertion, which counts as an attempt by the speaker to justify his claim, convincing the listner of its acceptability. The claim being made in prototypical Justification constructions (p, because q) is an assumption, not a fact; it corresponds to a conclusion drawn by the speaker, supported by the premise expressed in the second clause and warranted by a generic implicit premise. The account presented in this paper contests Sweetser’s (1990) distinction between epistemic causal conjunctions and speech act causal conjunctions: The act of concluding may be speaker-internal, but since it is asserted and then justified, it is not possible to dissociate the epistemic and the illocutionary domains within the field of argumentative texts.