This paper presents a comparative analysis of two Spanish constructions that are usually characterised as passive, namely the periphrastic or attributive passiveformed with the verb ser 'be' plus a participleand the reflexive passiveformed with third-person reflexive clitic se. An isomorphic functional approach is adopted whereby the inherent syntactic-semantic features of each construction are considered to be at the basis of their discourse-pragmatic uses. Using a corpus of local written news pieces from the Peninsular town of Salamanca, the grammatical expression of both the initiators and the endpoints of events in each construction is quantitatively and qualitatively analysed, paying special attention to their variable encoding and placement within the clause and the semantic correlates of formal variation. While attributive passives are used to predicate transitive events of topical endpoints, reflexive passives often conceptualise events as thetic, reducing transitivity and defocusing initiators. These meanings are projected onto the discoursepragmatic domain by favouring different interpretations of the role of human participants, particularly with respect to their involvement in events amenable to negative judgements. This supports the hypothesis that the syntax and semantics of each grammatical construction are undetachable from its communicative potential in specific contexts.Este art ıculo presenta un an alisis comparativo de dos construcciones del español caracterizadas habitualmente como pasivas: la perifr astica o atributiva, formada con el verbo ser y un participio, y la reflexiva, formada con el cl ıtico de tercera persona se. La investigaci on adopta un enfoque funcional isom orfico, por el cual se considera que los rasgos sint actico-sem anticos inherentes a una construcci on constituyen la base de sus usos discursivo-pragm aticos. A partir de un corpus de noticias escritas de la ciudad peninsular de Salamanca, se analiza cuantitativa y cualitativamente la configuraci on gramatical tanto de los iniciadores como de los t erminos de los eventos, prestando especial atenci on a su formulaci on y su colocaci on en la cl ausula y a los correlatos sem anticos de estas. Mientras que las pasivas atributivas predican eventos transitivos de t erminos topicales, las reflexivas suelen conceptualizar los eventos como t eticos, reduciendo la transitividad y desfocalizando al iniciador. Estos significados se proyectan en el dominio discursivo-pragm atico, favoreciendo distintas interpretaciones del papel de los participantes humanos, en particular en lo que se refiere a su implicaci on en eventos evaluados negativamente. Todo ello apoya la hip otesis de que la sintaxis y la sem antica de cada construcci on gramatical son inseparables de su potencial comunicativo en contextos espec ıficos.
